102 lines
3.4 KiB
C++
102 lines
3.4 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2007 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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//$Id$
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#include <boost/optional/optional.hpp>
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#include <boost/python.hpp>
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// boost::optional<T> to/from converter from John Wiegley
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template <typename T, typename TfromPy>
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struct object_from_python
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{
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object_from_python() {
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boost::python::converter::registry::push_back
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(&TfromPy::convertible, &TfromPy::construct,
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boost::python::type_id<T>());
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}
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};
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template <typename T, typename TtoPy, typename TfromPy>
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struct register_python_conversion
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{
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register_python_conversion() {
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boost::python::to_python_converter<T, TtoPy>();
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object_from_python<T, TfromPy>();
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}
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};
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template <typename T>
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struct python_optional : public boost::noncopyable
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{
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struct optional_to_python
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{
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static PyObject * convert(const boost::optional<T>& value)
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{
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return (value ? boost::python::to_python_value<T>()(*value) :
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boost::python::detail::none());
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}
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};
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struct optional_from_python
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{
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static void * convertible(PyObject * source)
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{
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using namespace boost::python::converter;
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if (source == Py_None)
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return source;
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const registration& converters(registered<T>::converters);
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if (implicit_rvalue_convertible_from_python(source,
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converters)) {
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rvalue_from_python_stage1_data data =
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rvalue_from_python_stage1(source, converters);
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return rvalue_from_python_stage2(source, data, converters);
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}
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return NULL;
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}
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static void construct(PyObject * source,
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boost::python::converter::rvalue_from_python_stage1_data * data)
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{
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using namespace boost::python::converter;
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void * const storage = ((rvalue_from_python_storage<T> *)
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data)->storage.bytes;
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if (data->convertible == source) // == None
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new (storage) boost::optional<T>(); // A Boost uninitialized value
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else
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new (storage) boost::optional<T>(*static_cast<T *>(data->convertible));
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data->convertible = storage;
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}
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};
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explicit python_optional() {
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register_python_conversion<boost::optional<T>,
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optional_to_python, optional_from_python>();
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}
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};
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