mapnik/include/expression.hpp
2006-03-31 10:32:02 +00:00

127 lines
2.9 KiB
C++

/*****************************************************************************
*
* 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 EXPRESSION_HPP
#define EXPRESSION_HPP
#include "value.hpp"
#include "filter_visitor.hpp"
namespace mapnik
{
template <typename FeatureT> class filter_visitor;
template <typename FeatureT>
class expression
{
public:
virtual value get_value(FeatureT const& feature) const=0;
virtual void accept(filter_visitor<FeatureT>& v)=0;
virtual expression<FeatureT>* clone() const=0;
virtual std::string to_string() const=0;
virtual ~expression() {}
};
template <typename FeatureT>
class literal : public expression<FeatureT>
{
public:
literal(int val)
: expression<FeatureT>(),
value_(val) {}
literal(double val)
: expression<FeatureT>(),
value_(val) {}
literal(std::string const& val)
: expression<FeatureT>(),
value_(val) {}
literal(literal const& other)
: expression<FeatureT>(),
value_(other.value_) {}
value get_value(FeatureT const& /*feature*/) const
{
return value_;
}
void accept(filter_visitor<FeatureT>& v)
{
v.visit(*this);
}
expression<FeatureT>* clone() const
{
return new literal(*this);
}
std::string to_string() const
{
return value_.to_expression_string();
}
~literal() {}
private:
value value_;
};
template <typename FeatureT>
class property : public expression<FeatureT>
{
public:
property(std::string const& name)
: expression<FeatureT>(),
name_(name)
{}
property(property const& other)
: expression<FeatureT>(),
name_(other.name_)
{}
value get_value(FeatureT const& feature) const
{
return feature[name_];
}
void accept(filter_visitor<FeatureT>& v)
{
v.visit(*this);
}
expression<FeatureT>* clone() const
{
return new property(*this);
}
std::string const& name() const
{
return name_;
}
std::string to_string() const
{
return "["+name_+"]";
}
~property() {}
private:
std::string name_;
};
}
#endif //EXPRESSION_HPP