tripwire-open-source/src/core/upperbound.h

93 lines
3.7 KiB
C++

//
// The developer of the original code and/or files is Tripwire, Inc.
// Portions created by Tripwire, Inc. are copyright (C) 2000-2018 Tripwire,
// Inc. Tripwire is a registered trademark of Tripwire, Inc. All rights
// reserved.
//
// This program is free software. The contents of this file are subject
// to the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version. You may redistribute it and/or modify it
// only in compliance with the GNU General Public License.
//
// This program is distributed in the hope that it will be useful.
// However, this program is distributed AS-IS WITHOUT ANY
// WARRANTY; INCLUDING THE IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS
// FOR A PARTICULAR PURPOSE. Please see the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
//
// Nothing in the GNU General Public License or any other license to use
// the code or files shall permit you to use Tripwire's trademarks,
// service marks, or other intellectual property without Tripwire's
// prior written consent.
//
// If you have any questions, please contact Tripwire, Inc. at either
// info@tripwire.org or www.tripwire.org.
//
///////////////////////////////////////////////////////////////////////////////
// upperbound.h
//
#ifndef __UPPERBOUND_H
#define __UPPERBOUND_H
/////////////////////////////////////////////////////////////////////////////////////////////
// Function name: template< class FwdIterT, class CmpObjT, class CmpFuncT >
// UpperBound
//
// Description : same as std::upper_bound except it allows 'less' to take
// parameters of dissimilar types. Therefore, *FwdIter need not be
// the same type as CmpObjT. Uses a binary search algorithm.
//
// Return type : FwdIterT : First element in the sequence [first, last)
// that is equal to or greater than 'obj' or
// 'last' if there is no such element.
//
// Argument : FwdIterT first : First element in sequence.
// Argument : FwdIterT last : Last element in sequence.
// Argument : const CmpObjT& obj: Object for which to search for upper bound.
// Argument : CmpFuncT less : Comparison function. Must return as 'std::less'.
// Will be called as: 'bool less( *FwdIterT, CmpObjT )'.
/////////////////////////////////////////////////////////////////////////////////////////////
template< class FwdIterT, class CmpObjT, class CmpFuncT > FwdIterT UpperBound( FwdIterT first, FwdIterT last, const CmpObjT& obj, CmpFuncT less )
{
// count elements in set
int nElemsInSet = 0;
FwdIterT iCur = first;
for (; iCur != last; ++iCur )
++nElemsInSet;
iCur = first;
while( 0 < nElemsInSet )
{
// go to halfway point
int iHalfWay = nElemsInSet/2;
FwdIterT iTemp = iCur;
for( int j = 0; j < iHalfWay; j++ )
iTemp++;
if( less( *iTemp, obj ) )
{
// start next search set at next elem with half of the last search set's elements
iCur = ++iTemp;
nElemsInSet -= iHalfWay + 1; // already searched ( iHalfway + 1 ) elems
}
else
{
// start next search set beginning with half of the last search set's elements
nElemsInSet = iHalfWay;
}
}
return iCur;
}
#endif // __UPPERBOUND_H