[857] | 1 | // Copyright David Abrahams and Nikolay Mladenov 2003.
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| 2 | // Distributed under the Boost Software License, Version 1.0. (See
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| 3 | // accompanying file LICENSE_1_0.txt or copy at
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| 4 | // http://www.boost.org/LICENSE_1_0.txt)
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| 5 | #ifndef RETURN_ARG_DWA2003719_HPP
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| 6 | # define RETURN_ARG_DWA2003719_HPP
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| 7 | # include <boost/python/default_call_policies.hpp>
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| 8 | # include <boost/python/detail/none.hpp>
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| 9 | # include <boost/python/detail/value_arg.hpp>
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| 10 |
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| 11 | # include <boost/type_traits/add_reference.hpp>
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| 12 | # include <boost/type_traits/add_const.hpp>
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| 13 |
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| 14 | # include <boost/mpl/int.hpp>
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| 15 |
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| 16 | # include <boost/static_assert.hpp>
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| 17 | # include <boost/python/refcount.hpp>
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| 18 |
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| 19 | # include <cstddef>
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| 20 |
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| 21 | namespace boost { namespace python {
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| 22 |
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| 23 | namespace detail
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| 24 | {
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| 25 | template <std::size_t>
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| 26 | struct return_arg_pos_argument_must_be_positive
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| 27 | # if defined(__GNUC__) && __GNUC__ >= 3 || defined(__EDG__)
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| 28 | {}
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| 29 | # endif
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| 30 | ;
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| 31 |
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| 32 | struct return_none
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| 33 | {
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| 34 | template <class T> struct apply
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| 35 | {
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| 36 | struct type
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| 37 | {
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| 38 | static bool convertible()
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| 39 | {
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| 40 | return true;
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| 41 | }
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| 42 |
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| 43 | PyObject *operator()( typename value_arg<T>::type ) const
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| 44 | {
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| 45 | return none();
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| 46 | }
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| 47 | };
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| 48 | };
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| 49 | };
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| 50 | }
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| 51 |
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| 52 | template <
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| 53 | std::size_t arg_pos=1
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| 54 | , class Base = default_call_policies
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| 55 | >
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| 56 | struct return_arg : Base
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| 57 | {
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| 58 | private:
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| 59 | BOOST_STATIC_CONSTANT(bool, legal = arg_pos > 0);
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| 60 |
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| 61 | public:
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| 62 | typedef typename mpl::if_c<
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| 63 | legal
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| 64 | , detail::return_none
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| 65 | , detail::return_arg_pos_argument_must_be_positive<arg_pos>
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| 66 | // we could default to the base result_converter in case or
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| 67 | // arg_pos==0 since return arg 0 means return result, but I
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| 68 | // think it is better to issue an error instead, cause it can
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| 69 | // lead to confusions
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| 70 | >::type result_converter;
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| 71 |
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| 72 | template <class ArgumentPackage>
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| 73 | static PyObject* postcall(ArgumentPackage const& args, PyObject* result)
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| 74 | {
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| 75 | // In case of arg_pos == 0 we could simply return Base::postcall,
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| 76 | // but this is redundant
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| 77 | BOOST_STATIC_ASSERT(arg_pos > 0);
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| 78 |
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| 79 | result = Base::postcall(args,result);
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| 80 | if (!result)
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| 81 | return 0;
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| 82 | Py_DECREF(result);
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| 83 | return incref( detail::get(mpl::int_<arg_pos-1>(),args) );
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| 84 | }
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| 85 | };
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| 86 |
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| 87 | template <
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| 88 | class Base = default_call_policies
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| 89 | >
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| 90 | struct return_self
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| 91 | : return_arg<1,Base>
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| 92 | {};
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| 93 |
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| 94 | }} // namespace boost::python
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| 95 |
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| 96 | #endif // RETURN_ARG_DWA2003719_HPP
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