boost/python/converter/shared_ptr_from_python.hpp

// Copyright David Abrahams 2002.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef SHARED_PTR_FROM_PYTHON_DWA20021130_HPP
# define SHARED_PTR_FROM_PYTHON_DWA20021130_HPP

# include <boost/python/handle.hpp>
# include <boost/python/converter/shared_ptr_deleter.hpp>
# include <boost/python/converter/from_python.hpp>
# include <boost/python/converter/rvalue_from_python_data.hpp>
# include <boost/python/converter/registered.hpp>
#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
# include <boost/python/converter/pytype_function.hpp>
#endif
# include <boost/shared_ptr.hpp>

namespace boost { namespace python { namespace converter { 

template <class T>
struct shared_ptr_from_python
{
    shared_ptr_from_python()
    {
        converter::registry::insert(&convertible, &construct, type_id<shared_ptr<T> >()
#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
                      , &converter::expected_from_python_type_direct<T>::get_pytype
#endif
                      );
    }

 private:
    static void* convertible(PyObject* p)
    {
        if (p == Py_None)
            return p;
        
        return converter::get_lvalue_from_python(p, registered<T>::converters);
    }
    
    static void construct(PyObject* source, rvalue_from_python_stage1_data* data)
    {
        void* const storage = ((converter::rvalue_from_python_storage<shared_ptr<T> >*)data)->storage.bytes;
        // Deal with the "None" case.
        if (data->convertible == source)
            new (storage) shared_ptr<T>();
        else
        {
            boost::shared_ptr<void> hold_convertible_ref_count(
              (void*)0, shared_ptr_deleter(handle<>(borrowed(source))) );
            // use aliasing constructor
            new (storage) shared_ptr<T>(
                hold_convertible_ref_count,
                static_cast<T*>(data->convertible));
        }
        
        data->convertible = storage;
    }
};

}}} // namespace boost::python::converter

#endif // SHARED_PTR_FROM_PYTHON_DWA20021130_HPP

Boost C++ Libraries

boost/python/converter/shared_ptr_from_python.hpp