180 lines
4.1 KiB
C++
180 lines
4.1 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: RowHeap.hxx
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//
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// Contents: Heap of rowsets.
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//
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// Classes: CRowHeap
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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 "rowcomp.hxx"
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#include "pcache.hxx"
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//+---------------------------------------------------------------------------
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//
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// Class: CRowHeap
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//
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// Purpose: Heap of rowsets.
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//
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// History: 05-Jun-95 KyleP Created.
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//
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// Notes: This heap implementation has two unusual characteristics:
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// a) It can return it's 'nth' element. This is used
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// to choose a likely centerpoint for approximate positioning.
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// b) It can be reinitialized. Used after positioning cursors
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// through some means external to the heap implementation.
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//
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//----------------------------------------------------------------------------
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class CRowHeap
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{
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public:
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CRowHeap( unsigned cCursor );
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void Init( CRowComparator * _pComparator,
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PMiniRowCache ** apCursor );
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void ReInit( int cValid );
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~CRowHeap() {}
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//
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// Iteration
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//
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PMiniRowCache::ENext Next( int iDir = 1 );
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inline BOOL IsHeapEmpty();
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//
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// Member access
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//
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inline PMiniRowCache * Top();
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inline PMiniRowCache * RemoveTop();
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void NthToTop( unsigned n );
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//
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// Miscellaneous.
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//
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PMiniRowCache::ENext Validate();
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void AdjustCacheSize( ULONG cRows );
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inline HROW const * TopHROWs();
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private:
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void Add( PMiniRowCache * pCursor );
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void MakeHeap( int cValid );
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void Reheap();
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# if CIDBG == 1
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void AssertCursorArrayIsValid();
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# endif // CIDBG
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inline unsigned Count();
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CRowComparator * _pComparator; // Compares two rows
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XArray<HROW> _ahrowTop; // Top HROW for each child. Used for bookmarks.
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int _iEnd; // Index to last valid cursor in _apCursor
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int _cCursor; // Number of elements in _apCursor.
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PMiniRowCache ** _apCursor; // One fat cursor per child (max).
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};
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inline HROW const * CRowHeap::TopHROWs()
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{
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return _ahrowTop.GetPointer();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CRowHeap::Top, public
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//
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// Returns: Rowcache with smallest element.
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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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inline PMiniRowCache * CRowHeap::Top()
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{
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Win4Assert( -1 != _iEnd );
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return( _apCursor[0] );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CRowHeap::RemoveTop, public
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//
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// Synopsis: 'Removes' row cache, by placing it beyond end of maintained
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// heap.
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//
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// Returns: Element which was 'removed'.
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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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inline PMiniRowCache * CRowHeap::RemoveTop()
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{
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Win4Assert( -1 != _iEnd );
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_ahrowTop[_apCursor[0]->Index()] = (HROW)-1;
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PMiniRowCache * pTemp = _apCursor[0];
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_apCursor[0] = _apCursor[_iEnd];
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_apCursor[_iEnd] = pTemp;
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_iEnd--;
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return( pTemp );
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CRowHeap::IsHeapEmpty, public
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//
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// Returns: TRUE if heap is empty.
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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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inline BOOL CRowHeap::IsHeapEmpty()
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{
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return (_iEnd == -1);
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CRowHeap::Count, public
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//
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// Returns: Number of elements in heap.
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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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inline unsigned CRowHeap::Count()
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{
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return( _iEnd + 1 );
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}
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