alpar@1253: /* -*- C++ -*-
alpar@1253:  * src/lemon/lin_expr.h - Part of LEMON, a generic C++ optimization library
alpar@1253:  *
alpar@1253:  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@1253:  * (Egervary Combinatorial Optimization Research Group, EGRES).
alpar@1253:  *
alpar@1253:  * Permission to use, modify and distribute this software is granted
alpar@1253:  * provided that this copyright notice appears in all copies. For
alpar@1253:  * precise terms see the accompanying LICENSE file.
alpar@1253:  *
alpar@1253:  * This software is provided "AS IS" with no warranty of any kind,
alpar@1253:  * express or implied, and with no claim as to its suitability for any
alpar@1253:  * purpose.
alpar@1253:  *
alpar@1253:  */
alpar@1253: 
alpar@1253: #ifndef LEMON_LIN_EXPR_H
alpar@1253: #define LEMON_LIN_EXPR_H
alpar@1253: 
alpar@1253: #include<vector>
alpar@1253: 
alpar@1253: 
alpar@1253: #include<map>
alpar@1253: 
alpar@1253: ///\file
alpar@1253: ///\brief Classes to handle linear expressions
alpar@1253: namespace lemon {
alpar@1253:   
alpar@1253:   /// Class to handle sparse linear expressions
alpar@1253:   template <class _V,class _C>
alpar@1253:   class SparseLinExpr : public std::map<_V, _C>
alpar@1253:   {
alpar@1253:   public:
alpar@1253:     typedef _V Var; 
alpar@1253:     typedef _C Coeff;
alpar@1253:     
alpar@1253:   protected:
alpar@1253:     typedef typename std::map<_V, _C> Base;
alpar@1253: 
alpar@1253:     Coeff const_comp;
alpar@1253:   public:
alpar@1253:     SparseLinExpr() { }
alpar@1253:     SparseLinExpr(const Var &v) : const_comp(v) {
alpar@1253:       Base::insert(std::make_pair(v, 1));
alpar@1253:     }
alpar@1253:     SparseLinExpr(const Coeff &v) : const_comp(v) {}
alpar@1253:     
alpar@1253:     void set(const Var &v,const Coeff &c) {
alpar@1253:       return Base::insert(std::make_pair(v, c));
alpar@1253:     }
alpar@1253: //     Coeff &operator[](const Var &v) { return data[v]; }
alpar@1253: //     const Coeff &operator[](const Var &v) const { return data[v]; }
alpar@1253: 
alpar@1253:     Coeff &constComp() { return const_comp; }
alpar@1253:     const Coeff &constComp() const { return const_comp; }
alpar@1253: 
alpar@1253:     ///Removes the components with zero coefficient.
alpar@1253:     void simplify() {
alpar@1253:       for (typename Base::iterator i=Base::begin(); i!=Base::end();) {
alpar@1253: 	typename Base::iterator j=i;
alpar@1253: 	++j;
alpar@1253: 	if ((*i).second==0) Base::erase(i);
alpar@1253: 	j=i;
alpar@1253:       }
alpar@1253:     }
alpar@1253:    
alpar@1253:   };
alpar@1253: 
alpar@1253: } //namespace lemon
alpar@1253: 
alpar@1253: #endif //LEMON_LIN_EXPR_H