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// Copyright David Abrahams and Nikolay Mladenov 2003.
// 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 RETURN_ARG_DWA2003719_HPP
# define RETURN_ARG_DWA2003719_HPP
# include <boost/python/default_call_policies.hpp>
# include <boost/python/detail/none.hpp>
# include <boost/python/detail/value_arg.hpp>
#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
# include <boost/python/converter/pytype_function.hpp>
#endif
# include <boost/python/detail/type_traits.hpp>
# include <boost/mpl/int.hpp>
# include <boost/mpl/at.hpp>
# include <boost/static_assert.hpp>
# include <boost/python/refcount.hpp>
# include <cstddef>
namespace boost { namespace python {
namespace detail
{
template <std::size_t>
struct return_arg_pos_argument_must_be_positive
# if defined(__GNUC__) || defined(__EDG__)
{}
# endif
;
struct return_none
{
template <class T> struct apply
{
struct type
{
static bool convertible()
{
return true;
}
PyObject *operator()( typename value_arg<T>::type ) const
{
return none();
}
#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
PyTypeObject const *get_pytype() const { return converter::expected_pytype_for_arg<T>::get_pytype() ; }
#endif
};
};
};
}
template <
std::size_t arg_pos=1
, class Base = default_call_policies
>
struct return_arg : Base
{
private:
BOOST_STATIC_CONSTANT(bool, legal = arg_pos > 0);
public:
typedef typename mpl::if_c<
legal
, detail::return_none
, detail::return_arg_pos_argument_must_be_positive<arg_pos>
// we could default to the base result_converter in case or
// arg_pos==0 since return arg 0 means return result, but I
// think it is better to issue an error instead, cause it can
// lead to confusions
>::type result_converter;
template <class ArgumentPackage>
static PyObject* postcall(ArgumentPackage const& args, PyObject* result)
{
// In case of arg_pos == 0 we could simply return Base::postcall,
// but this is redundant
BOOST_STATIC_ASSERT(arg_pos > 0);
result = Base::postcall(args,result);
if (!result)
return 0;
Py_DECREF(result);
return incref( detail::get(mpl::int_<arg_pos-1>(),args) );
}
template <class Sig>
struct extract_return_type : mpl::at_c<Sig, arg_pos>
{
};
};
template <
class Base = default_call_policies
>
struct return_self
: return_arg<1,Base>
{};
}} // namespace boost::python
#endif // RETURN_ARG_DWA2003719_HPP
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