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/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2007 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
*
*****************************************************************************/
//$Id$
#include <boost/optional/optional.hpp>
#include <boost/python.hpp>
// boost::optional<T> to/from converter from John Wiegley
template <typename T, typename TfromPy>
struct object_from_python
{
object_from_python() {
boost::python::converter::registry::push_back
(&TfromPy::convertible, &TfromPy::construct,
boost::python::type_id<T>());
}
};
template <typename T, typename TtoPy, typename TfromPy>
struct register_python_conversion
{
register_python_conversion() {
boost::python::to_python_converter<T, TtoPy>();
object_from_python<T, TfromPy>();
}
};
template <typename T>
struct python_optional : public boost::noncopyable
{
struct optional_to_python
{
static PyObject * convert(const boost::optional<T>& value)
{
return (value ? boost::python::to_python_value<T>()(*value) :
boost::python::detail::none());
}
};
struct optional_from_python
{
static void * convertible(PyObject * source)
{
using namespace boost::python::converter;
if (source == Py_None)
return source;
const registration& converters(registered<T>::converters);
if (implicit_rvalue_convertible_from_python(source,
converters)) {
rvalue_from_python_stage1_data data =
rvalue_from_python_stage1(source, converters);
return rvalue_from_python_stage2(source, data, converters);
}
return NULL;
}
static void construct(PyObject * source,
boost::python::converter::rvalue_from_python_stage1_data * data)
{
using namespace boost::python::converter;
void * const storage = ((rvalue_from_python_storage<T> *)
data)->storage.bytes;
if (data->convertible == source) // == None
new (storage) boost::optional<T>(); // A Boost uninitialized value
else
new (storage) boost::optional<T>(*static_cast<T *>(data->convertible));
data->convertible = storage;
}
};
explicit python_optional() {
register_python_conversion<boost::optional<T>,
optional_to_python, optional_from_python>();
}
};
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