permlib  0.2.6
Library for permutation computations
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include/permlib/transversal/explicit_transversal.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,
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00024 // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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00028 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00029 //
00030 // ---------------------------------------------------------------------------
00031 
00032 
00033 #ifndef EXPLICITTRANSVERSAL_H_
00034 #define EXPLICITTRANSVERSAL_H_
00035 
00036 #include <permlib/transversal/transversal.h>
00037 
00038 namespace permlib {
00039 
00041 template <class PERM>
00042 class ExplicitTransversal : public Transversal<PERM> {
00043 public:
00045     ExplicitTransversal(unsigned int n);
00046 
00047     virtual PERM* at(unsigned long val) const;
00048     virtual bool trivialByDefinition(const PERM& x, unsigned long to) const;
00049         
00050         virtual void permute(const PERM& g, const PERM& gInv);
00051         
00053 
00056         ExplicitTransversal<PERM> clone(const std::map<PERM*,typename PERM::ptr>& generatorChange) const;
00057 
00059     static const unsigned int m_statMaxDepth;
00060 protected:
00061     virtual void registerMove(unsigned long from, unsigned long to, const typename PERM::ptr &p);
00062 };
00063 
00064 //
00065 //     ----       IMPLEMENTATION
00066 //
00067 
00068 template <class PERM>
00069 const unsigned int ExplicitTransversal<PERM>::m_statMaxDepth = 1;
00070 
00071 template <class PERM>
00072 ExplicitTransversal<PERM>::ExplicitTransversal(unsigned int n_) 
00073         : Transversal<PERM>(n_) 
00074 { }
00075 
00076 template <class PERM>
00077 bool ExplicitTransversal<PERM>::trivialByDefinition(const PERM& x, unsigned long to) const {
00078         // we cannot infer this information from the transversal
00079         return false;
00080 }
00081 
00082 template <class PERM>
00083 PERM* ExplicitTransversal<PERM>::at(unsigned long val) const {
00084         if (!Transversal<PERM>::m_transversal[val])
00085                 return 0;
00086         return new PERM(*(Transversal<PERM>::m_transversal[val]));
00087 }
00088 
00089 template <class PERM>
00090 void ExplicitTransversal<PERM>::registerMove(unsigned long from, unsigned long to, const typename PERM::ptr &p) {
00091         Transversal<PERM>::registerMove(from, to, p);
00092 
00093         std::vector<boost::shared_ptr<PERM> > &transversal = Transversal<PERM>::m_transversal;
00094 
00095     if (!transversal[from])
00096         transversal[to] = boost::shared_ptr<PERM>(new PERM(*p));
00097     else {
00098         transversal[to] = boost::shared_ptr<PERM>(new PERM(*transversal[from]));
00099         (*transversal[to]) *= *p;
00100     }
00101 }
00102 
00103 template <class PERM>
00104 void ExplicitTransversal<PERM>::permute(const PERM& g, const PERM& gInv) {
00105         Transversal<PERM>::permute(g, gInv);
00106         BOOST_FOREACH(typename PERM::ptr& p, Transversal<PERM>::m_transversal) {
00107                 if (p) {
00108                         *p ^= gInv;
00109                         *p *= g;
00110                 }
00111         }
00112 }
00113 
00114 template <class PERM>
00115 ExplicitTransversal<PERM> ExplicitTransversal<PERM>::clone(const std::map<PERM*,typename PERM::ptr>& generatorChange) const {
00116         ExplicitTransversal<PERM> ret(*this);
00117         BOOST_FOREACH(typename PERM::ptr& p, ret.m_transversal) {
00118                 if (!p)
00119                         continue;
00120                 p = boost::shared_ptr<PERM>(new PERM(*p));
00121         }
00122         return ret;
00123 }
00124 
00125 }
00126 
00127 #endif // -- EXPLICITTRANSVERSAL_H_