259 lines
8.1 KiB
C++
259 lines
8.1 KiB
C++
//+-------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1992 - 1993.
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//
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// File: ColCompr.hxx
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//
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// Contents: Column compressor definitions
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//
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// Classes: CCompressedCol
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// CCompressedColHash
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// XCompressFreeVariant
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//
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// History: 22 Mar 1994 Alanw Created
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//
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//--------------------------------------------------------------------------
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#pragma once
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#ifdef DISPLAY_INCLUDES
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#pragma message( "#include <" __FILE__ ">..." )
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#endif
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#include <objcur.hxx>
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class CPathStore;
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//+-------------------------------------------------------------------------
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//
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// Class: CCompressedCol
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//
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// Purpose: An encapsulation of a compressed column
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//
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// Interface:
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//
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// Notes:
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//
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//--------------------------------------------------------------------------
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class CCompressedCol
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{
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public:
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enum CompType {
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FixedHash=1, // fixed data width hash table
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VarHash, // variable data width hash table
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PathCompr, // file path name compression
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StringVecCompr, // string vector compression
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};
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CCompressedCol(
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VARTYPE vtData,
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unsigned cbKey,
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CompType ComprType
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) :
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DataType( vtData ),
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_cbKeyWidth( cbKey ),
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_CompressionType( ComprType ) { }
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CCompressedCol( ) :
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DataType( VT_NULL ),
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_cbKeyWidth( sizeof ULONG ),
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_CompressionType( (CompType) 0 ) { }
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virtual ~CCompressedCol( ) { }
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virtual void AddData(PROPVARIANT const * const pvarnt,
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ULONG * pKey,
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GetValueResult& reIndicator) = 0;
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virtual GetValueResult GetData(PROPVARIANT * pvarnt,
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VARTYPE PreferredType,
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ULONG key = 0,
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PROPID prop = 0) = 0;
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virtual void FreeVariant(PROPVARIANT * pvarnt) = 0;
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virtual ULONG MemUsed(void) = 0;
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VARTYPE DataType;
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virtual CPathStore * GetPathStore()
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{
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return 0;
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}
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virtual BOOL FindData(PROPVARIANT const * const pvarnt,
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ULONG & rKey )
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{
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Win4Assert(!"FindData should not be called!");
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return FALSE;
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}
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protected:
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unsigned _cbKeyWidth; // width in row data (0 if compressed and no
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// key needed
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CompType _CompressionType;
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};
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//+-------------------------------------------------------------------------
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//
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// Class: CCompressedColHash
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//
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// Purpose: A compressed column which uses a hash table for
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// redundant value elimination.
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//
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// Interface: CCompressedCol
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//
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// Notes: The hash table code is generic and intended for
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// any fixed sized data. A hash table may be parameterized
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// for any particular data type by supplying the data
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// item width, an initial hash table size and optionally
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// a hash function. Items in the hash table are uniquely
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// identified by their offset in the data area.
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//
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// Entries are only added to the table, never removed.
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// This reduces storage requirements since reference
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// counts do not need to be stored.
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//
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//--------------------------------------------------------------------------
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typedef ULONG HASHKEY;
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const HASHKEY MAX_HASHKEY = 0xFFFFFFFF;
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class CCompressedColHash: public CCompressedCol
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{
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public:
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typedef ULONG (* PFNHASH) (BYTE *, USHORT);
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static ULONG DefaultHash(BYTE *pbData, USHORT cbData);
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CCompressedColHash(
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VARTYPE vtData,
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USHORT cbDataWidth,
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PFNHASH pfnHashFunction = DefaultHash);
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~CCompressedColHash();
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void AddData(PROPVARIANT const * const pvarnt,
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ULONG * pKey,
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GetValueResult& reIndicator);
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GetValueResult GetData(PROPVARIANT * pvarnt,
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VARTYPE PreferredType,
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ULONG key = 0,
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PROPID prop = 0);
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void FreeVariant(PROPVARIANT * pvarnt);
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ULONG MemUsed(void) {
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// return (_pAlloc->MemUsed());
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return _cbData;
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}
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protected:
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VOID _AddData(BYTE *pbData, USHORT cbDataSize, ULONG* pKey);
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VOID _Rehash(HASHKEY iKey, BYTE *pbData);
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VOID _GrowHashTable( void );
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HASHKEY* _IndexHashkey( HASHKEY iKey );
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ULONG _GetHashIndex( BYTE *pbData, USHORT cbData )
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{
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ULONG ulHash = _pfnHash( pbData, cbData );
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return ulHash%_cHashEntries;
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}
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void _ClearAll();
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HASHKEY* _pHashTable; // pointer to hash table
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PBYTE _pDataItems; // pointer to data items
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HASHKEY _cDataItems; // number of entries in pDataItems
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const USHORT _cbDataWidth; // width of each data item
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private:
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USHORT _NextHashSize( HASHKEY cItems, USHORT cHash );
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PFNHASH _pfnHash; // hash function
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USHORT _cHashEntries; // size of hash table
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USHORT _maxChain; // maximum hash chain length
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USHORT _fGrowthInProgress; // TRUE if _GrowHashTable active
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// CLEANCODE - the class should be changed to use CFixedAllocator
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ULONG _cbData; // size of allocation for compressed data
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PVOID _pData; // pointer to compression data
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ULONG _ulMemCounter; // Memory allocation counter
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//
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// Serialization.
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//
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CMutexSem _mtxSerialize; // Serialize Table access
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};
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//+-------------------------------------------------------------------------
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//
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// Method: CCompressedColHash::_IndexHashkey, protected inline
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//
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// Synopsis: Index a hash key and return a pointer to the hash
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// chain. The data will be found at the return value
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// plus sizeof (HASHKEY)
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//
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// Arguments: [iKey] - lookup key value
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//
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// Returns: HASHKEY*, pointer to the indexed item
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//
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// Notes:
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//
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//--------------------------------------------------------------------------
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inline HASHKEY* CCompressedColHash::_IndexHashkey(
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HASHKEY iKey
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) {
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Win4Assert(iKey > 0 && iKey <= _cDataItems);
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return (HASHKEY *) ((BYTE *)_pDataItems +
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(iKey - 1) * (sizeof (HASHKEY) + _cbDataWidth));
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}
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ULONG GuidHash(BYTE *pbData, USHORT cbData);
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//+-------------------------------------------------------------------------
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//
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// Class: XCompressFreeVariant
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//
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// Purpose: Safe pointer for variants created by compressors
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//
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// Interface:
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//
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// Notes: This class assures that variant structures are properly freed
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// in case of exception unwinds.
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//
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//--------------------------------------------------------------------------
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class XCompressFreeVariant
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{
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CCompressedCol * _pCompr;
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PROPVARIANT * _pVarnt;
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public:
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XCompressFreeVariant() :
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_pCompr( 0 ),
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_pVarnt( 0 )
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{
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END_CONSTRUCTION( XCompressFreeVariant );
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}
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~XCompressFreeVariant( )
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{
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if (_pCompr)
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_pCompr->FreeVariant(_pVarnt);
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}
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void Set( CCompressedCol * pCompr,
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PROPVARIANT * pVarnt
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) {
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_pCompr = pCompr;
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_pVarnt = pVarnt;
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}
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};
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