mapnik/include/math_expr.hpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/
//$Id$

#ifndef MATH_EXPR_HPP
#define MATH_EXPR_HPP

#include "expression.hpp"

namespace mapnik
{
    template <typename T>
    struct add
    {
        T operator () (T const& left, T const& right)
        {
            return left + right;
        }
        static std::string to_string()
        {
            return "+";
        } 
    };

    template <typename T>
    struct sub
    {
        T operator () (T const& left, T const& right)
        {
            return left - right;
        }
        static std::string to_string()
        {
            return "-";
        } 
    };
    
    template <typename T>
    struct mult
    {
        T operator () (T const& left, T const& right)
        {
            return left * right;
        }
        static std::string to_string()
        {
            return "*";
        } 
    };
    
    template <typename T>
    struct div
    {
        T operator () (T const& left, T const& right)
        {
            return left / right;
        }
        static std::string to_string()
        {
            return "/";
        } 
    };
    
    template <typename FeatureT,typename Op>
    struct math_expr_b : public expression<FeatureT>
    {
        math_expr_b(expression<FeatureT> const& left,
                    expression<FeatureT> const& right)
            : expression<FeatureT>(),
              left_(left.clone()), 
              right_(right.clone()) {}
        math_expr_b(math_expr_b const& other)
            : expression<FeatureT>(),
              left_(other.left_->clone()),
              right_(other.right_->clone()) {}

        value get_value(FeatureT const& feature) const
        {
            return Op ()(left_->get_value(feature),right_->get_value(feature));
        }

        void accept(filter_visitor<FeatureT>& v)
        {
            left_->accept(v);
            right_->accept(v);
            v.visit(*this);
        }

        expression<FeatureT>* clone() const
        {
            return new math_expr_b<FeatureT,Op>(*this);
        }
        std::string to_string() const
        {
            return "("+left_->to_string() + Op::to_string() + right_->to_string()+")";
        }

        ~math_expr_b() 
        {
            delete left_;
            delete right_;
        }
    private:
        expression<FeatureT>* left_;
        expression<FeatureT>* right_;	
    }; 
}

#endif //