/* -*- 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