permlib  0.2.6
Library for permutation computations
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include/permlib/change/simple_base_change.h
00001 // ---------------------------------------------------------------------------
00002 //
00003 //  This file is part of PermLib.
00004 //
00005 // Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
00006 // All rights reserved.
00007 // 
00008 // Redistribution and use in source and binary forms, with or without
00009 // modification, are permitted provided that the following conditions
00010 // are met:
00011 // 1. Redistributions of source code must retain the above copyright
00012 //    notice, this list of conditions and the following disclaimer.
00013 // 2. Redistributions in binary form must reproduce the above copyright
00014 //    notice, this list of conditions and the following disclaimer in the
00015 //    documentation and/or other materials provided with the distribution.
00016 // 3. The name of the author may not be used to endorse or promote products
00017 //    derived from this software without specific prior written permission.
00018 // 
00019 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00020 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00021 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00022 // IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00023 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00024 // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00025 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00026 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00027 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00028 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00029 //
00030 // ---------------------------------------------------------------------------
00031 
00032 
00033 #ifndef SIMPLEBASECHANGE_H_
00034 #define SIMPLEBASECHANGE_H_
00035 
00036 #include <permlib/change/base_change.h>
00037 
00038 namespace permlib {
00039 
00041 template<class PERM, class TRANS, class BASETRANSPOSE>
00042 class SimpleBaseChange : public BaseChange<PERM,TRANS> {
00043 public:
00045         explicit SimpleBaseChange(const BSGS<PERM,TRANS>&);
00046         
00048     template <class InputIterator>
00049     void change(BSGS<PERM,TRANS> &bsgs, InputIterator baseBegin, InputIterator baseEnd, bool skipRedundant = false) const;
00050 };
00051 
00052 //
00053 //     ----       IMPLEMENTATION
00054 //
00055 
00056 template<class PERM, class TRANS, class BASETRANSPOSE>
00057 SimpleBaseChange<PERM,TRANS,BASETRANSPOSE>::SimpleBaseChange(const BSGS<PERM,TRANS>&) 
00058         : BaseChange<PERM,TRANS>() 
00059 { }
00060 
00061 template<class PERM, class TRANS, class BASETRANSPOSE>
00062 template<class InputIterator>
00063 void SimpleBaseChange<PERM,TRANS,BASETRANSPOSE>::change(BSGS<PERM,TRANS> &bsgs, InputIterator baseBegin, InputIterator baseEnd, bool skipRedundant) const {
00064         if (baseBegin == baseEnd)
00065                 return;
00066 
00067         const unsigned long origOrder __attribute__((unused)) = bsgs.order();
00068         BASETRANSPOSE trans;
00069         
00070         unsigned int baseTargetPos = 0;
00071     while (baseBegin != baseEnd && baseTargetPos < bsgs.B.size()) {
00072                 unsigned long alpha = *baseBegin;
00073                 unsigned long beta = bsgs.B[baseTargetPos];
00074                 const bool redundant = skipRedundant && this->isRedundant(bsgs, baseTargetPos, alpha);
00075                 
00076                 if (!redundant && beta != alpha) {
00077                         unsigned int pos = bsgs.insertRedundantBasePoint(alpha);
00078                         for (; pos > baseTargetPos; --pos) {
00079                                 trans.transpose(bsgs, pos-1);
00080                                 ++BaseChange<PERM,TRANS>::m_statTranspositions;
00081                         }
00082                 }
00083                 
00084                 ++baseBegin;
00085                 if (!redundant)
00086                         ++baseTargetPos;
00087     }
00088         // insert remaining base points
00089         while (!skipRedundant && baseBegin != baseEnd) {
00090                 const unsigned long alpha = *baseBegin;
00091                 bsgs.insertRedundantBasePoint(alpha, baseTargetPos);
00092                 
00093                 ++baseBegin;
00094                 ++baseTargetPos;
00095         }
00096         
00097         bsgs.stripRedundantBasePoints(baseTargetPos);
00098         BaseChange<PERM,TRANS>::m_statScheierGeneratorsConsidered += trans.m_statScheierGeneratorsConsidered;
00099         
00100         BOOST_ASSERT(origOrder == bsgs.order());
00101 }
00102 
00103 }
00104 
00105 #endif // -- SIMPLEBASECHANGE_H_