orbit.h

// ---------------------------------------------------------------------------
//
//  This file is part of PermLib.
//
// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. The name of the author may not be used to endorse or promote products
//    derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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//
// ---------------------------------------------------------------------------
 
 
#ifndef ORBIT_H_
#define ORBIT_H_
 
#include <list>
 
#include <boost/foreach.hpp>
 
namespace permlib {

template<class PERM,class PDOMAIN>
class Orbit {
public:
        virtual ~Orbit() {}
        
        virtual bool contains(const PDOMAIN& val) const = 0;

        virtual const PDOMAIN& element() const = 0;
        
        typedef PERM PERMtype;
protected:

        template<class Action>
        void orbit(const PDOMAIN& beta, const std::list<typename PERM::ptr> &generators, Action a, std::list<PDOMAIN>& orbitList);
        

        template<class Action>
        void orbitUpdate(const PDOMAIN& beta, const std::list<typename PERM::ptr> &generators, const typename PERM::ptr &g, Action a, std::list<PDOMAIN>& orbitList);
        

        virtual bool foundOrbitElement(const PDOMAIN& alpha, const PDOMAIN& alpha_p, const typename PERM::ptr& p) = 0;
};
 
template <class PERM,class PDOMAIN>
template<class Action>
inline void Orbit<PERM,PDOMAIN>::orbit(const PDOMAIN& beta, const std::list<typename PERM::ptr> &generators, Action a, std::list<PDOMAIN>& orbitList) {
        if (orbitList.empty()) {
                orbitList.push_back(beta);
                foundOrbitElement(beta, beta, typename PERM::ptr());
        }
        BOOST_ASSERT( orbitList.size() >= 1 );
        
        PERMLIB_DEBUG(std::cout << "orbit of " << beta << std::endl;)
        typename std::list<PDOMAIN>::const_iterator it;
        for (it = orbitList.begin(); it != orbitList.end(); ++it) {
                const PDOMAIN &alpha = *it;
                BOOST_FOREACH(const typename PERM::ptr& p, generators) {
                        //std::cout << "         " << orbitList.size() << std::endl;
                        PDOMAIN alpha_p = a(*p, alpha);
                        if (alpha_p != alpha && foundOrbitElement(alpha, alpha_p, p))
                                orbitList.push_back(alpha_p);
                }
        }
        //std::cout << "orb size " << orbitList.size() << std::endl;
}
 
template <class PERM,class PDOMAIN>
template<class Action>
inline void Orbit<PERM,PDOMAIN>::orbitUpdate(const PDOMAIN& beta, const std::list<typename PERM::ptr> &generators, const typename PERM::ptr &g, Action a, std::list<PDOMAIN>& orbitList) {
        if (orbitList.empty()) {
                orbitList.push_back(beta);
                foundOrbitElement(beta, beta, typename PERM::ptr());
        }
        BOOST_ASSERT( orbitList.size() >= 1 );
        
        PERMLIB_DEBUG(std::cout << "orbiUpdate of " << beta << " and " << *g << std::endl;)
        const unsigned int oldSize = orbitList.size();
        // first, compute only ORBIT^g
        typename std::list<PDOMAIN>::const_iterator it;
        for (it = orbitList.begin(); it != orbitList.end(); ++it) {
                const PDOMAIN &alpha = *it;
                PDOMAIN alpha_g = a(*g, alpha);
                if (alpha_g != alpha && foundOrbitElement(alpha, alpha_g, g))
                        orbitList.push_back(alpha_g);
        }
        
        if (oldSize == orbitList.size())
                return;
        
        orbit(beta, generators, a, orbitList);
}
 
}
 
#endif // -- ORBIT_H_