475 lines
12 KiB
C++
475 lines
12 KiB
C++
//+---------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1991 - 2000.
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//
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// File: MCURSOR.CXX
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//
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// Contents: Merge Cursor
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//
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// Classes: CMergeCursor
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//
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// History: 06-May-91 BartoszM Created
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//
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// widHeap keyHeap
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//
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//----------------------------------------------------------------------------
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#include <pch.cxx>
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#pragma hdrstop
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#include <curstk.hxx>
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#include "mcursor.hxx"
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::CMergeCursor, public
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//
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// Synopsis: Create a cursor that merges a number of cursors.
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//
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// Arguments: [cCursor] -- count of cursors
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// [aCursor] -- array of pointers to cursors
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//
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// History: 06-May-91 BartoszM Created
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// 24-Jan-92 AmyA Modified to take CKeyCurArray as a
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// parameter.
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//
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// Notes: The cursors and the array will be deleted by destructor.
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// Leaves widHeap empty.
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//
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//----------------------------------------------------------------------------
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CMergeCursor::CMergeCursor( CKeyCurStack & stkCursor )
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: _keyHeap (),
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_widHeap ( stkCursor.Count() )
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{
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_widMax = 0; // not valid
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// Two step construction of the heap.
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// We have to make sure that all cursors have a valid key
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int cCursor = stkCursor.Count();
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int count = 0;
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// remove empty cursors. GetKey() can fail; don't leak cursors.
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for ( int i = 0; i < cCursor; i++ )
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{
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CKeyCursor *pCur = stkCursor.Get( i );
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Win4Assert( 0 != pCur );
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if ( 0 == pCur->GetKey() )
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stkCursor.Free( i );
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else
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count++;
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}
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XArray<CKeyCursor *> aCursor( count );
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for ( count = 0, i = 0; i < cCursor; i++ )
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{
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CKeyCursor *pCur = stkCursor.Get( i );
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if ( 0 != pCur )
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aCursor[ count++ ] = pCur;
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}
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delete [] stkCursor.AcqStack();
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_keyHeap.MakeHeap ( count, aCursor.Acquire() );
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if ( !_keyHeap.IsEmpty() )
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{
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_iid = _keyHeap.Top()->IndexId();
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_pid = _keyHeap.Top()->Pid();
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}
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ciDebugOut(( DEB_ITRACE, "merge cursor has %d cursors\n", count ));
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} //CMergeCursor
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::GetKey, public
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//
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// Synopsis: Get current key.
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//
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// History: 06-May-91 BartoszM Created
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//
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// Notes: Does not replenish widHeap
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// Current key is defined as:
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// 1. cur key of all cursors in widHeap, or,
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// 2. if widHeap empty, cur key of Top of key heap
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// (and cur key of all cursors in keyHeap with
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// the same cur key).
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//
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//----------------------------------------------------------------------------
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const CKeyBuf * CMergeCursor::GetKey()
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{
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if ( _widHeap.IsEmpty() )
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{
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if ( _keyHeap.IsEmpty() )
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return 0;
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return _keyHeap.Top()->GetKey();
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}
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return _widHeap.Top()->GetKey();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::WorkId, public
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//
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// Synopsis: Get current work id.
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//
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// History: 06-May-91 BartoszM Created
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//
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// Notes: Current wid is defined as:
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// 1. Cur wid of Top of widHeap (and cur wid of all
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// cursors in widHeap with the same wid-- however,
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// NextWid should not increment the others, since
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// they correspond to different index id's), or,
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// 2. if widHeap empty: replenish it
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//
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//----------------------------------------------------------------------------
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WORKID CMergeCursor::WorkId()
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{
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if ( _widHeap.IsEmpty() && !ReplenishWid() )
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return widInvalid;
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return _widHeap.Top()->WorkId();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::Occurrence, public
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//
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// Synopsis: Get current occurrence.
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//
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// History: 06-May-91 BartoszM Created
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//
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// Notes: Current occurrence is defined as:
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// 1. cur occ of Top of widHeap, or,
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// 2. if widHeap empty, replenish it.
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//
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//----------------------------------------------------------------------------
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OCCURRENCE CMergeCursor::Occurrence()
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{
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if ( _widHeap.IsEmpty() && !ReplenishWid() )
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return OCC_INVALID;
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return _widHeap.Top()->Occurrence();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::GetNextKey, public
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//
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// Synopsis: Move to next key
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//
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// Returns: Target key or NULL if no more keys
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//
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// History: 06-May-91 BartoszM Created
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//
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// Effects: Updates _iid _pid to the ones of the keyHeap top
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//
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// Notes: 1. Increment and move to keyHeap all cursors
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// from widHeap, or,
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// 2. if widHeap empty, increment and reheap all
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// cursors in keyHeap with the same cur key
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// as the Top.
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//
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//----------------------------------------------------------------------------
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const CKeyBuf * CMergeCursor::GetNextKey()
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{
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if ( ! _widHeap.IsEmpty() )
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{
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// move widHeap to keyHeap advancing all cursors
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CKeyCursor * cur;
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while ( ( cur = _widHeap.RemoveBottom() ) != 0 )
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{
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if ( cur->GetNextKey() == 0 )
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{
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delete cur;
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}
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else
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{
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_keyHeap.Add ( cur );
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}
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}
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}
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else if ( !_keyHeap.IsEmpty() )
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{
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// widHeap was empty. Advance all cursors
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// with the lowest key.
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CKeyBuf key = *_keyHeap.Top()->GetKey();
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do
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{
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if ( _keyHeap.Top()->GetNextKey() == 0 )
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{
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delete _keyHeap.RemoveTop();
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if ( _keyHeap.IsEmpty () )
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return 0;
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}
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else
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{
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_keyHeap.Reheap();
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}
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} while ( AreEqual(&key, _keyHeap.Top()->GetKey()) );
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}
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else
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return 0;
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if ( _keyHeap.IsEmpty() )
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return 0;
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CKeyCursor* cur = _keyHeap.Top();
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_pid = cur->Pid();
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_iid = cur->IndexId();
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return cur->GetKey();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::NextWorkId, public
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//
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// Synopsis: Move to next work id
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//
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// Returns: Target work id or widInvalid if no more wid's for current key
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//
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// Effects: Updates _iid to the one of the widHeap top
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//
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//
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// History: 06-May-91 BartoszM Created
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//
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// Notes: The same work id may be returned multiple times,
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// corresponding to multiple indexes.
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// 1. Increment Top of widHeap and reheap, or,
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// 2. if widHeap empty, replenish it
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//
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//----------------------------------------------------------------------------
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WORKID CMergeCursor::NextWorkId()
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{
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if ( _widHeap.IsEmpty() && !ReplenishWid() )
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return widInvalid;
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_widHeap.Top()->NextWorkId();
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_widHeap.Reheap();
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CKeyCursor* cur = _widHeap.Top();
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_iid = cur->IndexId();
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return cur->WorkId();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::NextOccurrence, public
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//
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// Synopsis: Move to next occurrence
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//
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// Returns: Target occurrence or OCC_INVALID if no more occurrences
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// for current (wid, index id) combination.
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//
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// History: 06-May-91 BartoszM Created
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//
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// Notes: 1. Increment Top of widHeap (do not reheap!), or,
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// 2. if widHeap empty, replenish it
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//
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//----------------------------------------------------------------------------
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OCCURRENCE CMergeCursor::NextOccurrence()
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{
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if ( _widHeap.IsEmpty() && !ReplenishWid() )
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return OCC_INVALID;
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return _widHeap.Top()->NextOccurrence();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::MaxOccurrence
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//
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// Synopsis: Returns max occurrence of current wid
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//
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// History: 20-Jun-96 SitaramR Created
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//
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//----------------------------------------------------------------------------
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OCCURRENCE CMergeCursor::MaxOccurrence()
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{
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if ( _widHeap.IsEmpty() )
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return OCC_INVALID;
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return _widHeap.Top()->MaxOccurrence();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::WorkIdCount, public
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//
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// Synopsis: return wid count
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//
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// History: 21-Jun-91 BartoszM Created
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//
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// Notes: 1. Sum up wid count of all cursors in widHeap, or,
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// 2. if widHeap empty, replenish it
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//
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//----------------------------------------------------------------------------
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ULONG CMergeCursor::WorkIdCount()
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{
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// Sum up all wid counts for the same key.
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// move all cursors with the same key to wid heap
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if (_widHeap.IsEmpty() && !ReplenishWid())
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{
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return 0;
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}
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int count = _widHeap.Count();
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ULONG widCount = 0;
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CKeyCursor **curVec = _widHeap.GetVector();
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while ( --count >= 0 )
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widCount += curVec[count]->WorkIdCount();
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// ciDebugOut (( DEB_ITRACE, "merge : wid count %ld\n", widCount ));
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return widCount;
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::OccurrenceCount, public
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//
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// Synopsis: return occurrence count
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//
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// History: 21-Jun-91 BartoszM Created
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//
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// Notes: 1. Return occ count of Top of widHeap
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// Occ counts of other cursors with the
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// same wid do not count! They will
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// be returned after NextWorkId is called
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// 2. if widHeap empty, replenish it
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//
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//----------------------------------------------------------------------------
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ULONG CMergeCursor::OccurrenceCount()
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{
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if ( _widHeap.IsEmpty() && !ReplenishWid() )
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{
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return 0;
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}
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return _widHeap.Top()->OccurrenceCount();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::HitCount, public
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//
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// Synopsis: return occurrence count
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//
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// History: 27-Feb-92 AmyA Created
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//
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// Notes: see notes for OccurrenceCount().
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//
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//----------------------------------------------------------------------------
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ULONG CMergeCursor::HitCount()
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{
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return OccurrenceCount();
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}
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//+---------------------------------------------------------------------------
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//
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// Member: CMergeCursor::ReplenishWid, protected
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//
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// Synopsis: Replenish the wid heap
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//
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// Returns: TRUE if successful, FALSE if key heap exhausted
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//
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// Effects: Updates _iid to the ones of the widHeap top
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//
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// History: 06-May-91 BartoszM Created
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//
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//----------------------------------------------------------------------------
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BOOL CMergeCursor::ReplenishWid()
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{
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if ( _keyHeap.IsEmpty() )
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{
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return FALSE;
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}
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// Move all cursors with the lowest key
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// to widHeap
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CKeyBuf key = *(_keyHeap.Top()->GetKey());
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do {
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CKeyCursor* cur = _keyHeap.RemoveTop();
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_widHeap.Add ( cur );
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} while ( !_keyHeap.IsEmpty()
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&& AreEqual( &key, _keyHeap.Top()->GetKey()) );
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_iid = _widHeap.Top()->IndexId();
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return TRUE;
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}
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//
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// Remove RefillStream() and FreeStream() once NTFS supports
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// sparse file operations on parts of a file when other parts
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// of the file are mapped. This won't happen any time soon.
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//
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void CMergeCursor::FreeStream()
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{
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ULONG cCursors = _keyHeap.Count();
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CKeyCursor **aCursors = _keyHeap.GetVector();
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ciDebugOut(( DEB_ITRACE, "free key heap has %d cursors\n", cCursors ));
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for ( ULONG i = 0; i < cCursors; i++ )
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aCursors[ i ]->FreeStream();
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cCursors = _widHeap.Count();
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aCursors = _widHeap.GetVector();
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ciDebugOut(( DEB_ITRACE, "free wid heap has %d cursors\n", cCursors ));
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for ( i = 0; i < cCursors; i++ )
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aCursors[ i ]->FreeStream();
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} //FreeStream
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void CMergeCursor::RefillStream()
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{
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ULONG cCursors = _keyHeap.Count();
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CKeyCursor **aCursors = _keyHeap.GetVector();
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ciDebugOut(( DEB_ITRACE, "refill key heap has %d cursors\n", cCursors ));
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for ( ULONG i = 0; i < cCursors; i++ )
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aCursors[ i ]->RefillStream();
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cCursors = _widHeap.Count();
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aCursors = _widHeap.GetVector();
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ciDebugOut(( DEB_ITRACE, "refill wid heap has %d cursors\n", cCursors ));
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for ( i = 0; i < cCursors; i++ )
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aCursors[ i ]->RefillStream();
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} //FreeStream
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