94 lines
2.3 KiB
C++
94 lines
2.3 KiB
C++
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//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1995 - 1998
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//
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// File: PosCache.hxx
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//
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// Contents: Positionable cache
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//
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// Classes: CMiniPositionableCache
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//
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// History: 05-Jun-95 KyleP Created
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include "pcache.hxx"
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//+---------------------------------------------------------------------------
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//
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// Class: CMiniPositionableCache
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//
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// Purpose: Row cache that supports random seek.
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//
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// History: 05-Jun-95 KyleP Created.
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//
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//----------------------------------------------------------------------------
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class CMiniPositionableCache : public PMiniRowCache
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{
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public:
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CMiniPositionableCache( int Index,
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IRowsetScroll * pRowset,
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unsigned cBindings,
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DBBINDING * pBindings,
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unsigned cbMaxLen,
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DBORDINAL iColumnBookmark,
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DBBKMARK cbBookmark );
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~CMiniPositionableCache();
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//
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// Iteration
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//
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ENext Next( int iDir = 1 );
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ENext MovePrev();
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ENext Seek( DBROWOFFSET lRows );
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ENext Seek( DBBKMARK cbBookmark, BYTE const * pbBookmark );
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ENext Seek( DBCOUNTITEM ulNumerator, DBCOUNTITEM ulDenominator );
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ENext LoadPrevRowData();
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virtual void FlushCache();
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inline HROW GetPrevHROW()
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{
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return _hrowPrev;
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}
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inline BYTE * GetPrevData() const
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{
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return ( _hrowPrev != DB_NULL_HROW ? _xpbPrevRow.GetPointer() : 0 );
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}
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private:
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//
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// Controlling rowset
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//
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IRowsetScroll * _pRowsetScroll;
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//
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// Support for bookmark(s). Used for positioning.
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//
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HACCESSOR _haccBookmark; // Accessor to fetch bookmark
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XArray<BYTE> _pbBookmark; // Bookmark for Next.
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XArray<BYTE> _pbBookmarkSeek; // Bookmark for Seek.
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BOOL _fUsingBookmark; // TRUE when bookmark column available
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DBCOUNTITEM _oBookmark; // Additional rows to be added beyond
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// bookmark.
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HROW _hrowPrev; // Handle to the previous row
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XPtrST<BYTE> _xpbPrevRow; // Previous row data
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};
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