redundant_base_point_insertion_strategy.h

// ---------------------------------------------------------------------------
//
//  This file is part of PermLib.
//
// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
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// ---------------------------------------------------------------------------
 
 
#ifndef REDUNDANT_BASE_POINT_INSERTION_STRATEGY_H_
#define REDUNDANT_BASE_POINT_INSERTION_STRATEGY_H_
 
namespace permlib {
 
template <class PERM, class TRANS>
struct BSGS;

template <class PERM, class TRANS>
class RedundantBasePointInsertionStrategy {
public:

        RedundantBasePointInsertionStrategy(const BSGS<PERM,TRANS> &bsgs) : m_bsgs(bsgs) {}
 
        // virtual destructor
        virtual ~RedundantBasePointInsertionStrategy() {}
        

        virtual int findInsertionPoint(dom_int beta, std::list<typename PERM::ptr> &S_i) const = 0;
protected:
        const BSGS<PERM,TRANS> &m_bsgs;
};

template <class PERM, class TRANS>
class TrivialRedundantBasePointInsertionStrategy : public RedundantBasePointInsertionStrategy<PERM,TRANS> {
public:
        TrivialRedundantBasePointInsertionStrategy(const BSGS<PERM,TRANS> &bsgs) : RedundantBasePointInsertionStrategy<PERM,TRANS>(bsgs) {}
        
        virtual int findInsertionPoint(dom_int beta, std::list<typename PERM::ptr> &S_i) const {
                const std::vector<dom_int> &B = RedundantBasePointInsertionStrategy<PERM,TRANS>::m_bsgs.B;
                const std::vector<TRANS> &U = RedundantBasePointInsertionStrategy<PERM,TRANS>::m_bsgs.U;
                for (unsigned int i=0; i<B.size(); ++i) {
                        if (beta == B[i])
                                return -i-1;
                }
                int pos = B.size();
                while (pos > 0 && U[pos-1].size() == 1)
                        --pos;
                return pos;
        }
};

template <class PERM, class TRANS>
class FirstRedundantBasePointInsertionStrategy : public RedundantBasePointInsertionStrategy<PERM,TRANS> {
public:
        FirstRedundantBasePointInsertionStrategy(const BSGS<PERM,TRANS> &bsgs) : RedundantBasePointInsertionStrategy<PERM,TRANS>(bsgs) {}
        
        virtual int findInsertionPoint(dom_int beta, std::list<typename PERM::ptr> &S_i) const {
                const std::vector<dom_int> &B = RedundantBasePointInsertionStrategy<PERM,TRANS>::m_bsgs.B;
                const std::list<typename PERM::ptr> &S = RedundantBasePointInsertionStrategy<PERM,TRANS>::m_bsgs.S;
                typename std::vector<dom_int>::const_iterator bIt = B.begin();
                int pos = B.size();
                for (unsigned int i=0; i<B.size(); ++i) {
                        if (beta == B[i])
                                return -i-1;
                        
                        ++bIt;
                        const PointwiseStabilizerPredicate<PERM> stab_i(B.begin(), bIt);
                        S_i.clear();
 
                        //TODO: don't create temporary copy
                        //      place directly into predicate
                        std::copy_if(S.begin(), S.end(), std::back_inserter(S_i), stab_i);
 
                        StabilizesPointPredicate<PERM> stab_beta(S_i.begin(), S_i.end());
                        if (stab_beta(beta)) {
                                pos = i+1;
                                break;
                        }
                }
                return pos;
        }
};
 
}
 
#endif // -- REDUNDANT_BASE_POINT_INSERTION_STRATEGY_H_