Source code of Windows XP (NT5)
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//+---------------------------------------------------------------------------
//
// Microsoft Windows
// Copyright (C) Microsoft Corporation, 1992 - 1994.
//
// File: varntcmp.hxx
//
// Contents: Variant Comparator
//
// Classes: CCompareVariants
//
// Functions:
//
// History: 5-01-95 srikants Created
//
//----------------------------------------------------------------------------
#pragma once
#include <compare.hxx>
class CPathStore;
//+---------------------------------------------------------------------------
//
// Class: CCompareVariants
//
// Purpose: A comparator for a pair of variants of the same type.
//
// History: 5-23-95 srikants Created
//
// Notes:
//
//----------------------------------------------------------------------------
class CCompareVariants
{
enum { eSortDescend = 0x1, eSortNullFirst = 0x2 };
public:
CCompareVariants() : _dir(0), _vt(VT_EMPTY), _iDirMult(1), _CompareFn(0) {}
// CCompareVariants( ULONG dir, VARENUM vt )
CCompareVariants( ULONG dir, VARTYPE vt )
{
Init( dir, vt );
}
// void Init( ULONG dir, VARENUM vt = VT_EMPTY )
void Init( ULONG dir, VARTYPE vt = VT_EMPTY )
{
_dir = dir;
_vt = vt;
_iDirMult = ( ( dir & eSortDescend ) != 0 ) ? -1 : 1;
_CompareFn = CComparators::GetComparator( (VARENUM) _vt );
}
int Compare( const PROPVARIANT * pVarnt1, const PROPVARIANT * pVarnt2 );
int GetDirMult() const { return _iDirMult; }
private:
void _UpdateCompare( VARTYPE vt );
ULONG _dir; // direction of comparison (ascent/descend)
int _iDirMult; // -1 for descending; +1 for ascending
FCmp _CompareFn; // Function used to compare variants of
// type '_vt'
// ULONG _vt; // Type of the variant currently initialized.
VARTYPE _vt; // Type of the variant currently initialized.
};
inline
int CCompareVariants::Compare( const PROPVARIANT * pVarnt1, const PROPVARIANT * pVarnt2 )
{
int iComp = 0;
Win4Assert( 0 != pVarnt1 && 0 != pVarnt2 );
VARTYPE vt1 = pVarnt1->vt;
VARTYPE vt2 = pVarnt2->vt;
if ( vt1 == VT_EMPTY )
{
if ( vt2 == VT_EMPTY )
iComp = 0;
else
iComp = (_dir & eSortNullFirst) != 0 ? -1 : 1;
}
else if ( vt2 == VT_EMPTY )
{
iComp = (_dir & eSortNullFirst) != 0 ? 1 : -1;
}
else
{
//
// Both are non empty.
//
if ( vt1 != vt2 )
{
iComp = vt2 - vt1;
}
else
{
if ( _vt != vt1 )
{
_UpdateCompare( (VARTYPE) vt1 );
}
if ( 0 != _CompareFn )
{
iComp = _CompareFn( *pVarnt1, *pVarnt2 );
}
}
iComp *= _iDirMult;
}
return iComp;
}
inline
void CCompareVariants::_UpdateCompare( VARTYPE vt )
{
_vt = vt;
_CompareFn = CComparators::GetComparator( (VARENUM) vt );
}