111 lines
2.9 KiB
Plaintext
111 lines
2.9 KiB
Plaintext
// Copyright David Abrahams and Nikolay Mladenov 2003.
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef RETURN_ARG_DWA2003719_HPP
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# define RETURN_ARG_DWA2003719_HPP
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# include <boost/python/default_call_policies.hpp>
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# include <boost/python/detail/none.hpp>
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# include <boost/python/detail/value_arg.hpp>
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#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
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# include <boost/python/converter/pytype_function.hpp>
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#endif
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# include <boost/type_traits/add_reference.hpp>
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# include <boost/type_traits/add_const.hpp>
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# include <boost/mpl/int.hpp>
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# include <boost/mpl/at.hpp>
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# include <boost/static_assert.hpp>
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# include <boost/python/refcount.hpp>
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# include <cstddef>
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namespace boost { namespace python {
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namespace detail
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{
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template <std::size_t>
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struct return_arg_pos_argument_must_be_positive
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# if defined(__GNUC__) || defined(__EDG__)
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{}
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# endif
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;
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struct return_none
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{
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template <class T> struct apply
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{
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struct type
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{
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static bool convertible()
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{
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return true;
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}
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PyObject *operator()( typename value_arg<T>::type ) const
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{
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return none();
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}
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#ifndef BOOST_PYTHON_NO_PY_SIGNATURES
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PyTypeObject const *get_pytype() const { return converter::expected_pytype_for_arg<T>::get_pytype() ; }
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#endif
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};
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};
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};
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}
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template <
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std::size_t arg_pos=1
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, class Base = default_call_policies
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>
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struct return_arg : Base
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{
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private:
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BOOST_STATIC_CONSTANT(bool, legal = arg_pos > 0);
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public:
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typedef typename mpl::if_c<
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legal
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, detail::return_none
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, detail::return_arg_pos_argument_must_be_positive<arg_pos>
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// we could default to the base result_converter in case or
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// arg_pos==0 since return arg 0 means return result, but I
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// think it is better to issue an error instead, cause it can
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// lead to confusions
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>::type result_converter;
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template <class ArgumentPackage>
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static PyObject* postcall(ArgumentPackage const& args, PyObject* result)
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{
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// In case of arg_pos == 0 we could simply return Base::postcall,
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// but this is redundant
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BOOST_STATIC_ASSERT(arg_pos > 0);
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result = Base::postcall(args,result);
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if (!result)
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return 0;
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Py_DECREF(result);
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return incref( detail::get(mpl::int_<arg_pos-1>(),args) );
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}
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template <class Sig>
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struct extract_return_type : mpl::at_c<Sig, arg_pos>
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{
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};
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};
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template <
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class Base = default_call_policies
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>
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struct return_self
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: return_arg<1,Base>
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{};
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}} // namespace boost::python
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#endif // RETURN_ARG_DWA2003719_HPP
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