122 lines
3 KiB
C++
122 lines
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, 1991 - 1998.
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//
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// File: keycur.hxx
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//
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// Contents: Key cursor classes
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//
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// Classes: CKeyCursor - 'The mother of all key cursors'
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//
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// History: 15-Apr-91 KyleP Created.
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// 26-Sep-91 BartoszM Made it a subclass
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// 18-Feb-92 AmyA Changed from CIndexCursor to
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// CKeyCursor.
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//
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//----------------------------------------------------------------------------
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#pragma once
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#include <misc.hxx>
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#include <ocursor.hxx>
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class CKeyBuf;
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//+---------------------------------------------------------------------------
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//
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// Class: CKeyCursor
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//
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// Purpose: The root class for all key cursors
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//
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// Interface:
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//
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// History: 15-Apr-91 KyleP Created.
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// 22-Jul-92 BartoszM added weight, rank, and max wid
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// 23-Jun-94 SitaramR removed _widMax.
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//
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//----------------------------------------------------------------------------
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class CKeyCursor : public COccCursor
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{
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public:
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CKeyCursor ( INDEXID iid, WORKID widMax )
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: COccCursor(iid, widMax),
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_lStatWeight( 0xffffffff ) {}
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CKeyCursor () {}
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virtual const CKeyBuf * GetKey() = 0;
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// GetNextKey should always update _pid!
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// and _lStatWeight
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virtual const CKeyBuf * GetNextKey() = 0;
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virtual ULONG OccurrenceCount() { return(0); }
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virtual WORKID MaxWorkId() { return(_widMax); }
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virtual LONG Rank()
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{
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LONG rank;
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//
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// Only string keys really have a rank with any meaning.
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//
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if ( GetKey()->IsValue() )
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{
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rank = MAX_QUERY_RANK;
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}
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else
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{
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OCCURRENCE maxOcc = MaxOccurrence();
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Win4Assert( maxOcc > 0 );
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Win4Assert( 0xffffffff != _lStatWeight );
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rank = RANK_MULTIPLIER * HitCount() * _lStatWeight / maxOcc;
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#if CIDBG == 1
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if ( rank < 0 )
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ciDebugOut(( DEB_WARN,
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"keycur rank 0x%x, maxOcc 0x%x, _lStatWeight 0x%x, HitCount 0x%x\n",
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rank, maxOcc, _lStatWeight, HitCount() ));
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#endif
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if (rank > MAX_QUERY_RANK)
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rank = MAX_QUERY_RANK;
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}
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return rank;
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}
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virtual void FreeStream() {}
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virtual void RefillStream() {}
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void RatioFinished ( ULONG& denom, ULONG& num )
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{
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Win4Assert ( !"RatioFinished called for random CKeyCursor" );
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}
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#ifdef CIEXTMODE
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void CiExtDump(void *ciExtSelf);
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#endif
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protected:
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void UpdateWeight()
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{
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ULONG widCount = WorkIdCount();
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if ( widCount == 0 )
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_lStatWeight = 0;
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else
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_lStatWeight = Log2(_widMax / widCount);
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}
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LONG _lStatWeight; // statistical weight for current key
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};
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