489 lines
12 KiB
C++
489 lines
12 KiB
C++
/*************************************************************************
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*
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* $RCSfile: hashtbl.cxx,v $
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*
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* $Revision: 1.1 $
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*
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* last change: $Author: nf $ $Date: 2001-04-11 09:52:26 $
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*
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* The Contents of this file are made available subject to the terms of
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* either of the following licenses
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*
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* - GNU Lesser General Public License Version 2.1
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* - Sun Industry Standards Source License Version 1.1
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*
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* Sun Microsystems Inc., October, 2000
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*
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* GNU Lesser General Public License Version 2.1
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* =============================================
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* Copyright 2000 by Sun Microsystems, Inc.
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* 901 San Antonio Road, Palo Alto, CA 94303, USA
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License version 2.1, as published by the Free Software Foundation.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*
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*
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* Sun Industry Standards Source License Version 1.1
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* =================================================
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* The contents of this file are subject to the Sun Industry Standards
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* Source License Version 1.1 (the "License"); You may not use this file
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* except in compliance with the License. You may obtain a copy of the
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* License at http://www.openoffice.org/license.html.
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*
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* Software provided under this License is provided on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
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* WITHOUT LIMITATION, WARRANTIES THAT THE SOFTWARE IS FREE OF DEFECTS,
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* MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE, OR NON-INFRINGING.
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* See the License for the specific provisions governing your rights and
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* obligations concerning the Software.
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*
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* The Initial Developer of the Original Code is: Sun Microsystems, Inc.
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*
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* Copyright: 2000 by Sun Microsystems, Inc.
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*
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* All Rights Reserved.
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*
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* Contributor(s): _______________________________________
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*
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*
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************************************************************************/
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#include "hashtbl.hxx"
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#include <string.h>
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// -------------------------------------------------------------
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// class HashItem
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//
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class HashItem
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{
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enum ETag { TAG_EMPTY, TAG_USED, TAG_DELETED };
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void* m_pObject;
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ETag m_Tag;
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char* m_Key;
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public:
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HashItem() { m_Tag = TAG_EMPTY; m_Key = NULL; m_pObject = NULL; }
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~HashItem() { delete [] m_Key; }
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bool IsDeleted() const
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{ return m_Tag == TAG_DELETED; }
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bool IsEmpty() const
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{ return m_Tag == TAG_DELETED || m_Tag == TAG_EMPTY; }
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bool IsFree() const
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{ return m_Tag == TAG_EMPTY; }
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bool IsUsed() const
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{ return m_Tag == TAG_USED; }
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void Delete()
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{ m_Tag = TAG_DELETED; delete [] m_Key; m_Key = new char[ 1 ]; m_Key[ 0 ] = 0; m_pObject = NULL; }
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const char *GetKey() const
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{ return m_Key; }
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void* GetObject() const
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{ return m_pObject; }
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void SetObject(const char * Key, void *pObject)
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{ m_Tag = TAG_USED; delete [] m_Key; m_Key = new char[ strlen( Key ) + 1 ]; strcpy( m_Key, Key ); m_pObject = pObject; }
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};
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#define MIN(a,b) (a)<(b)?(a):(b)
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#define MAX(a,b) (a)>(b)?(a):(b)
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// -------------------------------------------------------------
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// class HashTable
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//
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/*static*/ double HashTable::m_defMaxLoadFactor = 0.8;
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/*static*/ double HashTable::m_defDefGrowFactor = 2.0;
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HashTable::HashTable(unsigned long lSize, bool bOwner, double dMaxLoadFactor, double dGrowFactor)
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{
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m_lSize = lSize;
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m_bOwner = bOwner;
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m_lElem = 0;
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m_dMaxLoadFactor = MAX(0.5,MIN(1.0,dMaxLoadFactor)); // 0.5 ... 1.0
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m_dGrowFactor = MAX(1.3,(5.0,dGrowFactor)); // 1.3 ... 5.0
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m_pData = new HashItem [lSize];
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}
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HashTable::~HashTable()
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{
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// Wenn die HashTable der Owner der Objecte ist,
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// m<>ssen die Destruktoren separat gerufen werden.
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// Dies geschieht <20>ber die virtuelle Methode OnDeleteObject()
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//
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// Problem: Virtuelle Funktionen sind im Destructor nicht virtuell!!
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// Der Code mu<6D> deshalb ins Macro
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/*
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if (m_bOwner)
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{
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for (ULONG i=0; i<GetSize(); i++)
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{
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void *pObject = GetObjectAt(i);
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if (pObject != NULL)
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OnDeleteObject(pObject());
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}
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}
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*/
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// Speicher f<>r HashItems freigeben
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delete [] m_pData;
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}
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void* HashTable::GetObjectAt(unsigned long lPos) const
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// Gibt Objekt zur<75>ck, wenn es eines gibt, sonst NULL;
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{
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HashItem *pItem = &m_pData[lPos];
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return pItem->IsUsed() ? pItem->GetObject() : NULL;
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}
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void HashTable::OnDeleteObject(void*)
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{
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}
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unsigned long HashTable::Hash(const char *Key) const
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{
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// Hashfunktion von P.J. Weinberger
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// aus dem "Drachenbuch" von Aho/Sethi/Ullman
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unsigned long i,n;
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unsigned long h = 0;
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unsigned long g = 0;
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for (i=0,n=strlen( Key ); i<n; i++)
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{
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h = (h<<4) + (unsigned long)(unsigned short)Key[i];
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g = h & 0xf0000000;
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if (g != 0)
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{
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h = h ^ (g >> 24);
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h = h ^ g;
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}
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}
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return h % m_lSize;
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}
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unsigned long HashTable::DHash(const char* Key, unsigned long lOldHash) const
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{
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unsigned long lHash = lOldHash;
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unsigned long i,n;
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for (i=0,n=strlen( Key ); i<n; i++)
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{
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lHash *= 256L;
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lHash += (unsigned long)(unsigned short)Key[i];
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lHash %= m_lSize;
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}
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return lHash;
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}
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unsigned long HashTable::Probe(unsigned long lPos) const
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// gibt den Folgewert von lPos zur<75>ck
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{
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lPos++; if (lPos==m_lSize) lPos=0;
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return lPos;
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}
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bool HashTable::IsFull() const
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{
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return m_lElem>=m_lSize;
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}
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bool HashTable::Insert(const char * Key, void* pObject)
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// pre: Key ist nicht im Dictionary enthalten, sonst return FALSE
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// Dictionary ist nicht voll, sonst return FALSE
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// post: pObject ist unter Key im Dictionary; m_nElem wurde erh<72>ht
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{
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SmartGrow();
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if (IsFull())
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{
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return false;
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}
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if (FindPos(Key) != NULL )
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return false;
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unsigned long lPos = Hash(Key);
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HashItem *pItem = &m_pData[lPos];
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// first hashing
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//
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if (pItem->IsEmpty())
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{
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pItem->SetObject(Key, pObject);
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m_lElem++;
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return true;
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}
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// double hashing
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//
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lPos = DHash(Key,lPos);
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pItem = &m_pData[lPos];
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if (pItem->IsEmpty())
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{
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pItem->SetObject(Key, pObject);
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m_lElem++;
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return true;
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}
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// linear probing
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//
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do
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{
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lPos = Probe(lPos);
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pItem = &m_pData[lPos];
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}
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while(!pItem->IsEmpty());
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pItem->SetObject(Key, pObject);
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m_lElem++;
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return true;
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}
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HashItem* HashTable::FindPos(const char * Key) const
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// sucht den Key; gibt Refrenz auf den Eintrag (gefunden)
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// oder NULL (nicht gefunden) zur<75>ck
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//
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// pre: -
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// post: -
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{
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// first hashing
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//
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unsigned long lPos = Hash(Key);
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HashItem *pItem = &m_pData[lPos];
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if (pItem->IsUsed()
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&& !(strcmp( pItem->GetKey(), Key )))
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{
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return pItem;
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}
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// double hashing
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//
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if (pItem->IsDeleted() || pItem->IsUsed())
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{
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lPos = DHash(Key,lPos);
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pItem = &m_pData[lPos];
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if (pItem->IsUsed()
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&& (!strcmp( pItem->GetKey(), Key)))
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{
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return pItem;
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}
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// linear probing
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//
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if (pItem->IsDeleted() || pItem->IsUsed())
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{
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unsigned long n = 0;
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bool bFound = false;
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bool bEnd = false;
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do
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{
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n++;
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lPos = Probe(lPos);
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pItem = &m_pData[lPos];
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bFound = pItem->IsUsed()
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&& !( strcmp( pItem->GetKey(), Key ));
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bEnd = !(n<m_lSize || pItem->IsFree());
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}
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while(!bFound && !bEnd);
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return bFound ? pItem : NULL;
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}
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}
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// nicht gefunden
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//
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return NULL;
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}
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void* HashTable::Find(const char *Key) const
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// Gibt Verweis des Objektes zur<75>ck, das unter Key abgespeichert ist,
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// oder NULL wenn nicht vorhanden.
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//
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// pre: -
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// post: -
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{
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HashItem *pItem = FindPos(Key);
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if (pItem != NULL
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&& ( !strcmp( pItem->GetKey(), Key )))
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return pItem->GetObject();
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else
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return NULL;
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}
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void* HashTable::Delete( const char * Key)
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// L<>scht Objekt, das unter Key abgespeichert ist und gibt Verweis
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// darauf zur<75>ck.
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// Gibt NULL zur<75>ck, wenn Key nicht vorhanden ist.
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//
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// pre: -
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// post: Objekt ist nicht mehr enthalten; m_lElem dekrementiert
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// Wenn die HashTable der Owner ist, wurde das Object gel<65>scht
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{
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HashItem *pItem = FindPos(Key);
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if (pItem != NULL
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&& ( !strcmp( pItem->GetKey(), Key )))
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{
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void* pObject = pItem->GetObject();
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if (m_bOwner)
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OnDeleteObject(pObject);
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pItem->Delete();
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m_lElem--;
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return pObject;
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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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double HashTable::CalcLoadFactor() const
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// prozentuale Belegung der Hashtabelle berechnen
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{
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return double(m_lElem) / double(m_lSize);
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}
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void HashTable::SmartGrow()
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// Achtung: da die Objekte umkopiert werden, darf die OnDeleteObject-Methode
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// nicht gerufen werden
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{
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double dLoadFactor = CalcLoadFactor();
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if (dLoadFactor <= m_dMaxLoadFactor)
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return; // nothing to grow
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unsigned long lOldSize = m_lSize; // alte Daten sichern
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HashItem* pOldData = m_pData;
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m_lSize = unsigned long (m_dGrowFactor * m_lSize); // neue Gr<47><72>e
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m_pData = new HashItem[m_lSize]; // neue Daten holen
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// kein Speicher:
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// Zustand "Tabelle voll" wird in Insert abgefangen
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//
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if (m_pData == NULL)
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{
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m_lSize = lOldSize;
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m_pData = pOldData;
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return;
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}
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m_lElem = 0; // noch keine neuen Daten
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// Umkopieren der Daten
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//
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for (unsigned long i=0; i<lOldSize; i++)
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{
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HashItem *pItem = &pOldData[i];
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if (pItem->IsUsed())
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Insert(pItem->GetKey(),pItem->GetObject());
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}
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delete [] pOldData;
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}
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// Iterator ---------------------------------------------------------
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//
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HashTableIterator::HashTableIterator(HashTable const& aTable)
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: m_aTable(aTable)
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{
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m_lAt = 0;
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}
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void* HashTableIterator::GetFirst()
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{
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m_lAt = 0;
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return FindValidObject(true /* forward */);
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}
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void* HashTableIterator::GetLast()
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{
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m_lAt = m_aTable.GetSize() -1;
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return FindValidObject(false /* backward */);
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}
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void* HashTableIterator::GetNext()
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{
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if (m_lAt+1 >= m_aTable.GetSize())
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return NULL;
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m_lAt++;
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return FindValidObject(true /* forward */);
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}
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void* HashTableIterator::GetPrev()
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{
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if (m_lAt <= 0)
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return NULL;
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m_lAt--;
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return FindValidObject(false /* backward */);
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}
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void* HashTableIterator::FindValidObject(bool bForward)
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// Sucht nach einem vorhandenen Objekt ab der aktuellen
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// Position.
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//
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// pre: ab inkl. m_lAt soll die Suche beginnen
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// post: if not found then
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// if bForward == TRUE then
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// m_lAt == m_aTable.GetSize() -1
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// else
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// m_lAt == 0
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// else
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// m_lAt ist die gefundene Position
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{
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void *pObject = m_aTable.GetObjectAt(m_lAt);
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if (pObject != NULL)
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return pObject;
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while (pObject == NULL
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&& (bForward ? ((m_lAt+1) < m_aTable.GetSize())
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: m_lAt > 0))
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{
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if (bForward)
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m_lAt++;
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else
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m_lAt--;
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pObject = m_aTable.GetObjectAt(m_lAt);
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}
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return pObject;
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}
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