mapnik/bindings/python/mapnik_enumeration.hpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko, Jean-Francois Doyon
 *
 * 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
 *
 *****************************************************************************/
#ifndef MAPNIK_PYTHON_BINDING_ENUMERATION_INCLUDED
#define MAPNIK_PYTHON_BINDING_ENUMERATION_INCLUDED

namespace mapnik {

template <typename EnumWrapper>
class enumeration_ :
    public boost::python::enum_<typename EnumWrapper::native_type> 
{
        // some short cuts
        typedef boost::python::enum_<typename EnumWrapper::native_type> base_type;
        typedef typename EnumWrapper::native_type native_type;
    public:
        enumeration_() :
            base_type( EnumWrapper::get_name().c_str() )
        {
            init();
        }
        enumeration_(const char * python_alias) :
            base_type( python_alias )
        {
            init();
        }

    private:
        struct converter
        {
            static PyObject* convert(EnumWrapper const& v)
            {
                // Redirect conversion to a static method of our base class's
                // base class. A free template converter will not work because
                // the base_type::base typedef is protected.
                // Lets hope MSVC agrees that this is legal C++
                using namespace boost::python::converter;
                return base_type::base::to_python(
                        registered<native_type>::converters.m_class_object
                        ,  static_cast<long>( v ));

            }
        };

        void init() {
            boost::python::implicitly_convertible<native_type, EnumWrapper>();
            boost::python::to_python_converter<EnumWrapper, converter >();

            for (unsigned i = 0; i < EnumWrapper::MAX; ++i)
            {
                // Register the strings allready defined for this enum.
               base_type::value( EnumWrapper::get_string( i ), native_type( i ) );
            }
        }

};

} // end of namespace mapnik

#endif // MAPNIK_PYTHON_BINDING_ENUMERATION_INCLUDED