335 lines
12 KiB
C++
335 lines
12 KiB
C++
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//+-------------------------------------------------------------------------
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//
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// Copyright (C) 1992, Microsoft Corporation.
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//
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// File: sklist.hxx
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//
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// Contents: Macros that are used as templates for skip list
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// implementation.
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//
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// History: 06-May-92 Ricksa Created
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// 18-May-94 BruceMa Fixed scm memory leak in SKIP_LIST_ENTRY
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// 28-Jun-94 BruceMa Memory sift fixes
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//
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//--------------------------------------------------------------------------
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#ifndef __SKLIST_HXX__
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#define __SKLIST_HXX__
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//
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// BUGBUG: this unnessarily forces all skip lists in shared memory
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//
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#include <scmmem.hxx>
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// Used by insert/delete algorithms to preallocate array on stack.
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// This is valid for skip lists with <= 64K elements.
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#define SKIP_LIST_MAX 16
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// Set up the generator for skip list levels
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void InitSkLevelGenerator(void);
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// Get a level from the generator
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int GetSkLevel(int cMax);
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//+-------------------------------------------------------------------------
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//
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// Macro: SKIP_LIST_ENTRY
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//
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// Purpose: Implements an entry in a skip list.
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//
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// Interface: cLevel - returns number of forward pointers
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// GetForward - returns the ith forward pointer
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// SetForward - sets the ith forward pointer
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//
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// History: 06-May-92 Ricksa Created
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//
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// Notes: Base class is assumed to be defined with
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// INHERIT_VIRTUAL_UNWIND
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//
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//--------------------------------------------------------------------------
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#define SKIP_LIST_ENTRY(Entry, Base) \
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\
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class Entry : public Base \
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{ \
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public: \
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Entry( \
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const Base& Base##Value, \
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const int cEntries); \
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\
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virtual ~Entry##(void); \
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\
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int cLevel(void); \
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\
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Entry* GetForward(int iCur); \
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\
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void SetForward(int iCur, Entry* pnew); \
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Entry **GetBase(void); \
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\
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private: \
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\
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int _cEntries; \
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\
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Entry SCMBASED * SCMBASED * _ap##Base##Forward; \
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}; \
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\
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inline Entry::Entry( \
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const Base& Base##Value, \
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const int cEntries) : \
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Base(Base##Value), \
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_cEntries(cEntries), \
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_ap##Base##Forward(NULL) \
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{ \
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if (cEntries != 0) \
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{ \
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_ap##Base##Forward = (Entry **) \
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ScmMemAlloc(sizeof(Entry*) * _cEntries); \
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} \
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} \
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\
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\
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inline Entry##::~Entry##(void) \
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{ \
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\
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ScmMemFree(_ap##Base##Forward); \
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} \
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\
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inline int Entry##::cLevel(void) \
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{ \
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return _cEntries; \
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} \
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\
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inline Entry* Entry::GetForward(int iCur) \
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{ \
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return _ap##Base##Forward[iCur]; \
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} \
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\
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inline void Entry::SetForward(int iCur, Entry* pnew) \
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{ \
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_ap##Base##Forward[iCur] = pnew; \
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} \
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\
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inline Entry **Entry::GetBase(void) \
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{ \
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return _ap##Base##Forward; \
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} \
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//+-------------------------------------------------------------------------
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//
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// Macro: SKIP_LIST_HEAD
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//
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// Purpose: Implements head of a skip list.
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//
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// Interface: Search - find item in list
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// Insert - add new item to the list
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// Delete - remove item from the list
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// GetSkLevel - generate forward pointer for item in the list
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//
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// History: 06-May-92 Ricksa Created
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//
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//--------------------------------------------------------------------------
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#define SKIP_LIST_HEAD(Head, Entry, Base) \
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class Head : public CScmAlloc \
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{ \
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public: \
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\
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Head##( \
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const int cMaxLevel, \
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Base##& p##Base##MaxKey); \
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\
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~Head##(void); \
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\
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Entry * Search(const Base##& skey); \
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\
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void Insert(Entry *p##Entry##New); \
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\
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void Delete(Base##& Base##Key); \
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\
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int GetSkLevel(void); \
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\
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Entry * First(void); \
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\
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Entry * Next(Entry *); \
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Entry * GetList(void); \
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\
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private: \
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\
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Entry * FillUpdateArray( \
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const Base *Base##Key, \
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Entry **pp##Entry##Update); \
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\
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int _cCurrentMaxLevel; \
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\
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int _cMaxLevel; \
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\
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Entry SCMBASED * _p##Entry##Head; \
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}; \
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\
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inline Head##::##Head##( \
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const int cMaxLevel, \
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Base& Base##MaxKey) : _cCurrentMaxLevel(0), _cMaxLevel(cMaxLevel) \
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{ \
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_p##Entry##Head = new Entry(Base##MaxKey, cMaxLevel); \
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\
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if (_p##Entry##Head && _p##Entry##Head->GetBase()) \
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{ \
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for (int i = 0; i < cMaxLevel; i++) \
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{ \
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_p##Entry##Head->SetForward(i, _p##Entry##Head); \
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} \
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} \
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} \
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\
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inline Head##::~##Head##(void) \
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{ \
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if (_p##Entry##Head) \
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{ \
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if (_p##Entry##Head->GetBase()) \
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{ \
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while (_p##Entry##Head->GetForward(0) != _p##Entry##Head) \
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{ \
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Delete(*_p##Entry##Head->GetForward(0)); \
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} \
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} \
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\
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delete (Entry *) _p##Entry##Head; \
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} \
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} \
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\
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inline Entry *##Head##::Search(const Base##& Base##Key) \
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{ \
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Entry *p##Entry##Search = _p##Entry##Head; \
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\
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register int CmpResult = -1; \
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\
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for (int i = _cCurrentMaxLevel - 1; i >= 0; i--) \
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{ \
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while ((CmpResult = \
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p##Entry##Search->GetForward(i)->Compare(Base##Key)) < 0) \
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{ \
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p##Entry##Search = p##Entry##Search->GetForward(i); \
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} \
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\
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if (CmpResult == 0) \
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{ \
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break; \
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} \
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} \
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\
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return (CmpResult == 0) \
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? (Entry *) p##Entry##Search->GetForward(i) : NULL; \
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} \
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\
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inline Entry *##Head##::FillUpdateArray( \
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const Base *Base##Key, \
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Entry **pp##Entry##Update) \
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{ \
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Entry *p##Entry##Search = _p##Entry##Head; \
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if (p##Entry##Search) \
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{ \
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\
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for (int i = _cCurrentMaxLevel - 1; i >= 0; i--) \
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{ \
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while (p##Entry##Search->GetForward(i)->Compare(*##Base##Key) < 0) \
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{ \
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p##Entry##Search = p##Entry##Search->GetForward(i); \
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} \
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\
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pp##Entry##Update[i] = p##Entry##Search; \
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} \
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\
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return p##Entry##Search->GetForward(0); \
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} \
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else \
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{ \
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return NULL; \
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} \
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} \
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\
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inline void Head##::Insert(Entry *p##Entry##New) \
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{ \
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Entry *ap##Entry##Update[SKIP_LIST_MAX]; \
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\
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if (p##Entry##New && _p##Entry##Head) \
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{ \
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FillUpdateArray(p##Entry##New, ap##Entry##Update); \
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\
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int iNewLevel = p##Entry##New->cLevel(); \
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\
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if (iNewLevel > _cCurrentMaxLevel) \
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{ \
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for (int i = _cCurrentMaxLevel; i < iNewLevel; i++) \
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{ \
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ap##Entry##Update[i] = _p##Entry##Head; \
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} \
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\
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_cCurrentMaxLevel = iNewLevel; \
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} \
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\
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for (int i = 0; i < iNewLevel ; i++) \
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{ \
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p##Entry##New->SetForward(i, ap##Entry##Update[i]->GetForward(i)); \
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ap##Entry##Update[i]->SetForward(i, p##Entry##New); \
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} \
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} \
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} \
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\
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inline void Head##::Delete(Base##& Base##Key) \
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{ \
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Entry *ap##Entry##Update[SKIP_LIST_MAX]; \
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\
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Entry *p##Entry##Delete = \
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FillUpdateArray(&##Base##Key, ap##Entry##Update); \
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\
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for (int i = 0; i < _cCurrentMaxLevel; i++) \
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{ \
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if (ap##Entry##Update[i]->GetForward(i) != p##Entry##Delete) \
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{ \
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break; \
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} \
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\
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ap##Entry##Update[i]->SetForward(i, p##Entry##Delete->GetForward(i)); \
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} \
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delete p##Entry##Delete; \
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\
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while (_cCurrentMaxLevel > 1 && \
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_p##Entry##Head->GetForward(_cCurrentMaxLevel - 1) == \
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_p##Entry##Head) \
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{ \
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_cCurrentMaxLevel--; \
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} \
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} \
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\
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inline int Head::GetSkLevel(void) \
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{ \
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return ::GetSkLevel( \
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(_cCurrentMaxLevel != _cMaxLevel) ? _cCurrentMaxLevel + 1 : _cMaxLevel); \
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} \
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\
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inline Entry *Head::First(void) \
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{ \
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Entry *p##Entry##First = _p##Entry##Head->GetForward(0); \
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\
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return (p##Entry##First != _p##Entry##Head) ? p##Entry##First : NULL; \
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} \
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\
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inline Entry *Head::Next(Entry *p##Entry##From) \
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{ \
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Entry *p##Entry##To = p##Entry##From->GetForward(0); \
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\
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return (p##Entry##To != _p##Entry##Head) ? p##Entry##To : NULL; \
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} \
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\
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inline Entry *Head::GetList(void) \
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{ \
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\
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return _p##Entry##Head; \
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} \
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#endif // __SKLIST_HXX__
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