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more/math/equi_set.h

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//  Copyright (C) 2001--2002  Petter Urkedal
//
//  This file is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This file is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//  As a special exception, you may use this file as part of a free
//  software library without restriction.  Specifically, if other files
//  instantiate templates or use macros or inline functions from this
//  file, or you compile this file and link it with other files to
//  produce an executable, this file does not by itself cause the
//  resulting executable to be covered by the GNU General Public
//  License.  This exception does not however invalidate any other
//  reasons why the executable file might be covered by the GNU General
//  Public License.
//
//  $Id: equi_set.h,v 1.3 2002/09/01 12:01:45 petter_urkedal Exp $

#ifndef MORE_GEN_EQUI_SET_H
#define MORE_GEN_EQUI_SET_H

///\if experimental

namespace more {
namespace gen {

  /** \class equi_set equi_set.h more/math/equi_set.h
      A set of equidistant numbers. */
  template<typename Number>
    struct equi_set
    {
        equi_set(Number begin, Number end, Number step)
            : m_beg(begin), m_end(end), m_step(step) {}

        bool contains(Number i)
        {
            return !(i < m_beg) && i < m_end;
        }

        equi_set& operator|=(equi_set const& rhs) const;

        friend Number below(equi_set const& x) const {return x.m_beg-m_step;}
        friend Number min(equi_set const& x) const { return x.m_beg; }
        friend Number max(equi_set const& x) const { return x.m_end-m_step; }
        friend Number above(equi_set const& x) const { return x.m_end; }

      private:
        Number m_beg;
        Number m_end;
        Number m_step;
    };

  template<typename Number>
    equi_set<Number>&
    equi_set<Number>::operator|=(equi_set const& rhs)
    {
        if (m_step == rhs.m_step) {
            if ((m_beg - rhs.m_beg) % m_step == 0) {
                if (rhs.m_beg < m_beg) {
                    if (rhs.m_end < m_beg)
                        goto fail;
                    m_beg = rhs.m_beg;
                }
                if (m_end < rhs.m_end) {
                    if (m_end < rhs.m_beg)
                        goto fail;
                    m_end = rhs.m_end;
                }
                return *this;
            }
            throw std::logic_error("more::math::equi_set::operator|=: "
                                   "Case is not implemented.");
        }
      fail:
        throw std::logic_error("more::math::equi_set::operator|=: "
                               "Result set can not be represented.");
    }

}}

///\endif

#endif

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