BWAPI: SPAR/AIModule/BWTA/vendors/CGAL/CGAL/Polynomial/internal/Alternation

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00001 // Copyright (c) 2005  Stanford University (USA).
00002 // All rights reserved.
00003 //
00004 // This file is part of CGAL (www.cgal.org); you can redistribute it and/or
00005 // modify it under the terms of the GNU Lesser General Public License as
00006 // published by the Free Software Foundation; version 2.1 of the License.
00007 // See the file LICENSE.LGPL distributed with CGAL.
00008 //
00009 // Licensees holding a valid commercial license may use this file in
00010 // accordance with the commercial license agreement provided with the software.
00011 //
00012 // This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
00013 // WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
00014 //
00015 // $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.5-branch/Kinetic_data_structures/include/CGAL/Polynomial/internal/Alternation_counter.h $
00016 // $Id: Alternation_counter.h 28567 2006-02-16 14:30:13Z lsaboret $
00017 // 
00018 //
00019 // Author(s)     : Daniel Russel <drussel@alumni.princeton.edu>
00020 
00021 #ifndef CGAL_ALTERNATION_COUNTER_H
00022 #define CGAL_ALTERNATION_COUNTER_H
00023 
00024 #include <CGAL/Polynomial/basic.h>
00025 
00026 CGAL_POLYNOMIAL_BEGIN_NAMESPACE
00027 
00032 
00033 
00036 template <class NT>
00037 class Alternation_counter
00038 {
00039     public:
00040         Alternation_counter():num_alternations_(0),
00041             last_sign_(EXTENDED_ZERO), count_uncertain_(false),
00042             parity_uncertain_(false),
00043             last_was_uncertain_(false) {}
00045         void push_back(const NT &i) {
00046             Extended_sign sn= extended_sign(i);
00047 
00048             if (sn == EXTENDED_ZERO) {
00049 
00050             }
00051             else if (sn==EXTENDED_UNKNOWN) {
00052                 if (last_was_uncertain_) {
00053                     count_uncertain_=true;
00054                     parity_uncertain_=true;
00055                 } else last_was_uncertain_=true;
00056             }
00057             else {
00058                 if (sn==EXTENDED_NEGATIVE
00059                 && last_sign_ == EXTENDED_POSITIVE) {
00060                     ++num_alternations_;
00061                 } else if (sn==EXTENDED_POSITIVE
00062                 && last_sign_==EXTENDED_NEGATIVE) {
00063                     ++num_alternations_;
00064                 }
00065                 else {
00066                     if (last_was_uncertain_) {
00067                         count_uncertain_=true;
00068                     }
00069 // parity is still good
00070                 }
00071                 last_sign_=sn;
00072                 last_was_uncertain_=false;
00073             }
00074         }
00075 
00077 
00080         std::size_t number_of_alternations() const
00081         {
00082             return num_alternations_;
00083         }
00085         bool is_uncertain() const
00086         {
00087             return count_uncertain_ || last_was_uncertain_;
00088         }
00090         bool parity_uncertain() const
00091         {
00092             return parity_uncertain_;
00093         }
00094     protected:
00095         std::size_t num_alternations_;
00096 
00097         Extended_sign last_sign_;
00098 
00099         bool count_uncertain_;
00100         bool parity_uncertain_;
00101         bool last_was_uncertain_;
00102 
00103 };
00104 
00105 CGAL_POLYNOMIAL_END_NAMESPACE;
00106 #endif