524 lines
12 KiB
C++
524 lines
12 KiB
C++
/**
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* @file llskiplist.h
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* @brief skip list implementation
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*
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* $LicenseInfo:firstyear=2001&license=viewergpl$
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*
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* Copyright (c) 2001-2009, Linden Research, Inc.
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*
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* Second Life Viewer Source Code
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* The source code in this file ("Source Code") is provided by Linden Lab
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* to you under the terms of the GNU General Public License, version 2.0
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* ("GPL"), unless you have obtained a separate licensing agreement
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* ("Other License"), formally executed by you and Linden Lab. Terms of
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* the GPL can be found in doc/GPL-license.txt in this distribution, or
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* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
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*
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* There are special exceptions to the terms and conditions of the GPL as
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* it is applied to this Source Code. View the full text of the exception
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* in the file doc/FLOSS-exception.txt in this software distribution, or
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* online at
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* http://secondlifegrid.net/programs/open_source/licensing/flossexception
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*
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* By copying, modifying or distributing this software, you acknowledge
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* that you have read and understood your obligations described above,
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* and agree to abide by those obligations.
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*
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* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
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* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
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* COMPLETENESS OR PERFORMANCE.
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* $/LicenseInfo$
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*/
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#ifndef LL_LLSKIPLIST_H
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#define LL_LLSKIPLIST_H
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#include "llrand.h"
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#include "llrand.h"
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// NOTA BENE: Insert first needs to be < NOT <=
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// Binary depth must be >= 2
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template <class DATA_TYPE, S32 BINARY_DEPTH = 10>
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class LLSkipList
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{
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public:
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typedef BOOL (*compare)(const DATA_TYPE& first, const DATA_TYPE& second);
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typedef compare insert_func;
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typedef compare equals_func;
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void init();
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// basic constructor
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LLSkipList();
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// basic constructor including sorter
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LLSkipList(insert_func insert_first, equals_func equals);
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~LLSkipList();
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inline void setInsertFirst(insert_func insert_first);
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inline void setEquals(equals_func equals);
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inline BOOL addData(const DATA_TYPE& data);
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inline BOOL checkData(const DATA_TYPE& data);
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// returns number of items in the list
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inline S32 getLength() const; // NOT a constant time operation, traverses entire list!
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inline BOOL moveData(const DATA_TYPE& data, LLSkipList *newlist);
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inline BOOL removeData(const DATA_TYPE& data);
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// remove all nodes from the list but do not delete data
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inline void removeAllNodes();
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// place mCurrentp on first node
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inline void resetList();
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// return the data currently pointed to, set mCurentOperatingp to that node and bump mCurrentp
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inline DATA_TYPE getCurrentData();
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// same as getCurrentData() but a more intuitive name for the operation
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inline DATA_TYPE getNextData();
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// remove the Node at mCurentOperatingp
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// leave mCurrentp and mCurentOperatingp on the next entry
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inline void removeCurrentData();
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// reset the list and return the data currently pointed to, set mCurentOperatingp to that node and bump mCurrentp
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inline DATA_TYPE getFirstData();
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class LLSkipNode
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{
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public:
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LLSkipNode()
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: mData(0)
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{
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S32 i;
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for (i = 0; i < BINARY_DEPTH; i++)
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{
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mForward[i] = NULL;
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}
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}
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LLSkipNode(DATA_TYPE data)
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: mData(data)
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{
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S32 i;
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for (i = 0; i < BINARY_DEPTH; i++)
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{
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mForward[i] = NULL;
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}
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}
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~LLSkipNode()
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{
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}
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DATA_TYPE mData;
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LLSkipNode *mForward[BINARY_DEPTH];
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private:
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// Disallow copying of LLSkipNodes by not implementing these methods.
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LLSkipNode(const LLSkipNode &);
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LLSkipNode &operator=(const LLSkipNode &);
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};
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static BOOL defaultEquals(const DATA_TYPE& first, const DATA_TYPE& second)
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{
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return first == second;
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}
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private:
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LLSkipNode mHead;
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LLSkipNode *mUpdate[BINARY_DEPTH];
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LLSkipNode *mCurrentp;
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LLSkipNode *mCurrentOperatingp;
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S32 mLevel;
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insert_func mInsertFirst;
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equals_func mEquals;
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private:
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// Disallow copying of LLSkipNodes by not implementing these methods.
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LLSkipList(const LLSkipList &);
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LLSkipList &operator=(const LLSkipList &);
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};
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///////////////////////
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//
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// Implementation
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//
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// Binary depth must be >= 2
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::init()
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{
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S32 i;
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for (i = 0; i < BINARY_DEPTH; i++)
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{
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mHead.mForward[i] = NULL;
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mUpdate[i] = NULL;
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}
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mLevel = 1;
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mCurrentp = *(mHead.mForward);
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mCurrentOperatingp = *(mHead.mForward);
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}
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// basic constructor
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline LLSkipList<DATA_TYPE, BINARY_DEPTH>::LLSkipList()
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: mInsertFirst(NULL),
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mEquals(defaultEquals)
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{
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init();
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}
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// basic constructor including sorter
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline LLSkipList<DATA_TYPE, BINARY_DEPTH>::LLSkipList(insert_func insert,
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equals_func equals)
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: mInsertFirst(insert),
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mEquals(equals)
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{
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init();
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline LLSkipList<DATA_TYPE, BINARY_DEPTH>::~LLSkipList()
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{
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removeAllNodes();
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::setInsertFirst(insert_func insert_first)
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{
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mInsertFirst = insert_first;
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::setEquals(equals_func equals)
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{
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mEquals = equals;
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline BOOL LLSkipList<DATA_TYPE, BINARY_DEPTH>::addData(const DATA_TYPE& data)
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{
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S32 level;
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LLSkipNode *current = &mHead;
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LLSkipNode *temp;
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// find the pointer one in front of the one we want
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if (mInsertFirst)
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(mInsertFirst(temp->mData, data)))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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else
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(temp->mData < data))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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// we're now just in front of where we want to be . . . take one step forward
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current = *current->mForward;
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// now add the new node
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S32 newlevel;
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for (newlevel = 1; newlevel <= mLevel && newlevel < BINARY_DEPTH; newlevel++)
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{
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if (ll_frand() < 0.5f)
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break;
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}
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LLSkipNode *snode = new LLSkipNode(data);
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if (newlevel > mLevel)
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{
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mHead.mForward[mLevel] = NULL;
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mUpdate[mLevel] = &mHead;
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mLevel = newlevel;
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}
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for (level = 0; level < newlevel; level++)
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{
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snode->mForward[level] = mUpdate[level]->mForward[level];
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mUpdate[level]->mForward[level] = snode;
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}
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return TRUE;
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline BOOL LLSkipList<DATA_TYPE, BINARY_DEPTH>::checkData(const DATA_TYPE& data)
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{
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S32 level;
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LLSkipNode *current = &mHead;
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LLSkipNode *temp;
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// find the pointer one in front of the one we want
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if (mInsertFirst)
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(mInsertFirst(temp->mData, data)))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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else
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(temp->mData < data))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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// we're now just in front of where we want to be . . . take one step forward
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current = *current->mForward;
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if (current)
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{
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return mEquals(current->mData, data);
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}
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return FALSE;
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}
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// returns number of items in the list
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline S32 LLSkipList<DATA_TYPE, BINARY_DEPTH>::getLength() const
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{
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U32 length = 0;
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for (LLSkipNode* temp = *(mHead.mForward); temp != NULL; temp = temp->mForward[0])
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{
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length++;
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}
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return length;
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline BOOL LLSkipList<DATA_TYPE, BINARY_DEPTH>::moveData(const DATA_TYPE& data, LLSkipList *newlist)
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{
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BOOL removed = removeData(data);
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BOOL added = newlist->addData(data);
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return removed && added;
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}
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline BOOL LLSkipList<DATA_TYPE, BINARY_DEPTH>::removeData(const DATA_TYPE& data)
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{
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S32 level;
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LLSkipNode *current = &mHead;
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LLSkipNode *temp;
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// find the pointer one in front of the one we want
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if (mInsertFirst)
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(mInsertFirst(temp->mData, data)))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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else
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{
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for (level = mLevel - 1; level >= 0; level--)
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{
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temp = *(current->mForward + level);
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while ( (temp)
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&&(temp->mData < data))
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{
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current = temp;
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temp = *(current->mForward + level);
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}
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*(mUpdate + level) = current;
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}
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}
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// we're now just in front of where we want to be . . . take one step forward
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current = *current->mForward;
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if (!current)
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{
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// empty list or beyond the end!
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return FALSE;
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}
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// is this the one we want?
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if (!mEquals(current->mData, data))
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{
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// nope!
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return FALSE;
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}
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else
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{
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// do we need to fix current or currentop?
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if (current == mCurrentp)
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{
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mCurrentp = current->mForward[0];
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}
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if (current == mCurrentOperatingp)
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{
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mCurrentOperatingp = current->mForward[0];
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}
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// yes it is! change pointers as required
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for (level = 0; level < mLevel; level++)
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{
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if (mUpdate[level]->mForward[level] != current)
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{
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// cool, we've fixed all the pointers!
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break;
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}
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mUpdate[level]->mForward[level] = current->mForward[level];
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}
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// clean up cuurent
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delete current;
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// clean up mHead
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while ( (mLevel > 1)
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&&(!mHead.mForward[mLevel - 1]))
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{
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mLevel--;
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}
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}
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return TRUE;
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}
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// remove all nodes from the list but do not delete data
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::removeAllNodes()
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{
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LLSkipNode *temp;
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// reset mCurrentp
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mCurrentp = *(mHead.mForward);
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while (mCurrentp)
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{
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temp = mCurrentp->mForward[0];
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delete mCurrentp;
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mCurrentp = temp;
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}
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S32 i;
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for (i = 0; i < BINARY_DEPTH; i++)
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{
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mHead.mForward[i] = NULL;
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mUpdate[i] = NULL;
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}
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mCurrentp = *(mHead.mForward);
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mCurrentOperatingp = *(mHead.mForward);
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}
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// place mCurrentp on first node
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::resetList()
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{
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mCurrentp = *(mHead.mForward);
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mCurrentOperatingp = *(mHead.mForward);
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}
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// return the data currently pointed to, set mCurentOperatingp to that node and bump mCurrentp
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline DATA_TYPE LLSkipList<DATA_TYPE, BINARY_DEPTH>::getCurrentData()
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{
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if (mCurrentp)
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{
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mCurrentOperatingp = mCurrentp;
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mCurrentp = mCurrentp->mForward[0];
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return mCurrentOperatingp->mData;
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}
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else
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{
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//return NULL; // causes compile warning
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return (DATA_TYPE)0; // equivalent, but no warning
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}
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}
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// same as getCurrentData() but a more intuitive name for the operation
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline DATA_TYPE LLSkipList<DATA_TYPE, BINARY_DEPTH>::getNextData()
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{
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if (mCurrentp)
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{
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mCurrentOperatingp = mCurrentp;
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mCurrentp = mCurrentp->mForward[0];
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return mCurrentOperatingp->mData;
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}
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else
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{
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//return NULL; // causes compile warning
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return (DATA_TYPE)0; // equivalent, but no warning
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}
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}
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// remove the Node at mCurentOperatingp
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// leave mCurrentp and mCurentOperatingp on the next entry
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline void LLSkipList<DATA_TYPE, BINARY_DEPTH>::removeCurrentData()
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{
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if (mCurrentOperatingp)
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{
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removeData(mCurrentOperatingp->mData);
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}
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}
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// reset the list and return the data currently pointed to, set mCurentOperatingp to that node and bump mCurrentp
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template <class DATA_TYPE, S32 BINARY_DEPTH>
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inline DATA_TYPE LLSkipList<DATA_TYPE, BINARY_DEPTH>::getFirstData()
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{
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mCurrentp = *(mHead.mForward);
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mCurrentOperatingp = *(mHead.mForward);
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if (mCurrentp)
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{
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mCurrentOperatingp = mCurrentp;
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mCurrentp = mCurrentp->mForward[0];
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return mCurrentOperatingp->mData;
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}
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else
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{
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//return NULL; // causes compile warning
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return (DATA_TYPE)0; // equivalent, but no warning
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}
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}
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#endif
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