// Copyright (c) 2005  Stanford University (USA).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.5-branch/Kinetic_data_structures/include/CGAL/Polynomial/internal/Sign_variations_counter.h $
// $Id: Sign_variations_counter.h 28567 2006-02-16 14:30:13Z lsaboret $
// 
//
// Author(s)     : Daniel Russel <drussel@alumni.princeton.edu>

#ifndef CGAL_POLYNOMIAL_SIGN_VARIATIONS_COUNTER_H
#define CGAL_POLYNOMIAL_SIGN_VARIATIONS_COUNTER_H

#include <CGAL/Polynomial/basic.h>

CGAL_POLYNOMIAL_BEGIN_INTERNAL_NAMESPACE

struct Sign_variations_counter
{
    template<class Iterator>
        static
        unsigned int sign_variations(const Iterator& first,
        const Iterator& beyond,
    bool stop_if_more_than_one = false) {
        Iterator it1 = first;
        Iterator last = beyond;
        last--;

        int count(0);

        while ( it1 != beyond && (int)(*it1) == (int)CGAL::ZERO ) { it1++; }

        while ( it1 != last && it1 != beyond ) {
            Iterator it2 = it1;
            it2++;
            while ( it2 != beyond && (int)(*it2) == (int)CGAL::ZERO ) { it2++; }

            if ( it2 != beyond && (int)(*it1) != (int)(*it2) ) {
                if ( stop_if_more_than_one && count > 1 ) { break; }
                count++;
            }
            it1 = it2;
        }

        return count;
    }

    template<class Iterator>
        unsigned int operator()(const Iterator& first,
        const Iterator& beyond,
        bool stop_if_more_than_one = false) const
    {
        return sign_variations(first, beyond, stop_if_more_than_one);
    }

};

CGAL_POLYNOMIAL_END_INTERNAL_NAMESPACE
#endif                                            // CGAL_POLYNOMIAL_SIGN_VARIATIONS_COUNTER_H
