symmetric_group_transversal.h

// ---------------------------------------------------------------------------
//
//  This file is part of PermLib.
//
// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
// All rights reserved.
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// ---------------------------------------------------------------------------
 
 
#ifndef SYMMETRIC_GROUP_TRANSVERSAL_H_
#define SYMMETRIC_GROUP_TRANSVERSAL_H_
 
#include <boost/iterator/counting_iterator.hpp>
 
namespace permlib {
 
template<class PERM>
struct SymmetricGroup;

template<class PERM>
class SymmetricGroupTransversal {
        public:

                SymmetricGroupTransversal(const SymmetricGroup<PERM>* sg, unsigned int basePos) : symmetricGroup(sg), m_basePos(basePos) {}
                
                PERM* at(unsigned long val) const {
                        for (unsigned int i=0; i<m_basePos; ++i) {
                                if ((symmetricGroup->B)[i] == val)
                                        return 0;
                        }
                        
                        PERM* p = new PERM(symmetricGroup->B.size());
                        p->setTransposition((symmetricGroup->B)[m_basePos],val);
                        return p;
                }

                unsigned int size() const { return symmetricGroup->n - m_basePos; }
                
                boost::counting_iterator<unsigned int> begin() const { return boost::counting_iterator<unsigned int>(0); };
                boost::counting_iterator<unsigned int> end() const { return boost::counting_iterator<unsigned int>(symmetricGroup->n-m_basePos ); };
        private:
                const SymmetricGroup<PERM>* symmetricGroup;
                unsigned int m_basePos;
};
 
}
 
#endif // SYMMETRIC_GROUP_TRANSVERSAL_H_