193 lines
6.4 KiB
C#
193 lines
6.4 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.Region.ScriptEngine.Yengine
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{
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/**
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* @brief Implements a queue of XMRInstance's.
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* Do our own queue to avoid shitty little mallocs.
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*
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* Note: looping inst.m_NextInst and m_PrevInst back to itself
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* when inst is removed from a queue is purely for debug.
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*/
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public class XMRInstQueue
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{
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private XMRInstance m_Head = null;
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private XMRInstance m_Tail = null;
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/**
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* @brief Insert instance at head of queue (in front of all others)
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* @param inst = instance to insert
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*/
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public void InsertHead(XMRInstance inst)
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{
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if((inst.m_PrevInst != inst) || (inst.m_NextInst != inst))
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throw new Exception("already in list");
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inst.m_PrevInst = null;
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if((inst.m_NextInst = m_Head) == null)
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m_Tail = inst;
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else
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m_Head.m_PrevInst = inst;
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m_Head = inst;
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}
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/**
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* @brief Insert instance at tail of queue (behind all others)
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* @param inst = instance to insert
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*/
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public void InsertTail(XMRInstance inst)
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{
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if((inst.m_PrevInst != inst) || (inst.m_NextInst != inst))
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throw new Exception("already in list");
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inst.m_NextInst = null;
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if((inst.m_PrevInst = m_Tail) == null)
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m_Head = inst;
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else
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m_Tail.m_NextInst = inst;
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m_Tail = inst;
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}
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/**
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* @brief Insert instance before another element in queue
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* @param inst = instance to insert
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* @param after = element that is to come after one being inserted
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*/
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public void InsertBefore(XMRInstance inst, XMRInstance after)
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{
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if((inst.m_PrevInst != inst) || (inst.m_NextInst != inst))
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throw new Exception("already in list");
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if(after == null)
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InsertTail(inst);
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else
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{
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inst.m_NextInst = after;
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inst.m_PrevInst = after.m_PrevInst;
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if(inst.m_PrevInst == null)
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m_Head = inst;
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else
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inst.m_PrevInst.m_NextInst = inst;
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after.m_PrevInst = inst;
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}
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}
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/**
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* @brief Peek to see if anything in queue
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* @returns first XMRInstance in queue but doesn't remove it
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* null if queue is empty
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*/
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public XMRInstance PeekHead()
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{
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return m_Head;
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}
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/**
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* @brief Remove first element from queue, if any
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* @returns null if queue is empty
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* else returns first element in queue and removes it
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*/
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public XMRInstance RemoveHead()
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{
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XMRInstance inst = m_Head;
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if(inst != null)
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{
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if((m_Head = inst.m_NextInst) == null)
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m_Tail = null;
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else
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m_Head.m_PrevInst = null;
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inst.m_NextInst = inst;
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inst.m_PrevInst = inst;
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}
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return inst;
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}
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/**
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* @brief Remove last element from queue, if any
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* @returns null if queue is empty
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* else returns last element in queue and removes it
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*/
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public XMRInstance RemoveTail()
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{
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XMRInstance inst = m_Tail;
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if(inst != null)
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{
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if((m_Tail = inst.m_PrevInst) == null)
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m_Head = null;
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else
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m_Tail.m_NextInst = null;
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inst.m_NextInst = inst;
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inst.m_PrevInst = inst;
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}
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return inst;
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}
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/**
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* @brief Remove arbitrary element from queue, if any
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* @param inst = element to remove (assumed to be in the queue)
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* @returns with element removed
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*/
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public void Remove(XMRInstance inst)
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{
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XMRInstance next = inst.m_NextInst;
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XMRInstance prev = inst.m_PrevInst;
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if((prev == inst) || (next == inst))
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throw new Exception("not in a list");
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if(next == null)
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{
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if(m_Tail != inst)
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throw new Exception("not in this list");
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m_Tail = prev;
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}
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else
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next.m_PrevInst = prev;
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if(prev == null)
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{
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if(m_Head != inst)
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throw new Exception("not in this list");
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m_Head = next;
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}
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else
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prev.m_NextInst = next;
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inst.m_NextInst = inst;
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inst.m_PrevInst = inst;
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}
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}
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}
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