/* -*- C++ -*-

 * src/lemon/lin_expr.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Combinatorial Optimization Research Group, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_LIN_EXPR_H

#define LEMON_LIN_EXPR_H

#include<vector>

#include<map>

///\file

///\brief Classes to handle linear expressions

namespace lemon {

  /// Class to handle sparse linear expressions

  template <class _V,class _C>

  class SparseLinExpr : public std::map<_V, _C>

  {

  public:

    typedef _V Var; 

    typedef _C Coeff;

  protected:

    typedef typename std::map<_V, _C> Base;

    Coeff const_comp;

  public:

    SparseLinExpr() { }

    SparseLinExpr(const Var &v) : const_comp(v) {

      Base::insert(std::make_pair(v, 1));

    }

    SparseLinExpr(const Coeff &v) : const_comp(v) {}

    void set(const Var &v,const Coeff &c) {

      return Base::insert(std::make_pair(v, c));

    }

//     Coeff &operator[](const Var &v) { return data[v]; }

//     const Coeff &operator[](const Var &v) const { return data[v]; }

    Coeff &constComp() { return const_comp; }

    const Coeff &constComp() const { return const_comp; }

    ///Removes the components with zero coefficient.

    void simplify() {

      for (typename Base::iterator i=Base::begin(); i!=Base::end();) {

	typename Base::iterator j=i;

	++j;

	if ((*i).second==0) Base::erase(i);

	j=i;

      }

    }

  };

} //namespace lemon

#endif //LEMON_LIN_EXPR_H