group_sorter.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.
// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// ---------------------------------------------------------------------------
 
 
#ifndef GROUPSORTER_H
#define GROUPSORTER_H
 
#include <boost/foreach.hpp>
 
namespace permlib {

template <class PERM>
class GroupSorter {
public:

        template <class InputIterator>
        GroupSorter(unsigned int size, InputIterator begin, InputIterator end) :
                // initialize m_size elements with value m_size
                m_order(size, size),
                m_base(begin, end)
        {
                InputIterator it;
                unsigned int i = 0;
                // base elements first
                for (it = begin; it != end; ++it) {
                        m_order[*it] = ++i;
                }
        }

        bool operator() (PERM a, PERM b) const {
                BOOST_FOREACH(unsigned long beta, m_base) {
                        if (m_order[a / beta] < m_order[b / beta])
                                return true;
                }
                return false;
        }
private:
        std::vector<unsigned long> m_order;
        std::vector<unsigned long> m_base;
};
 
}
 
#endif // -- GROUPSORTER_H