69 lines
2.1 KiB
C++
69 lines
2.1 KiB
C++
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// Copyright David Abrahams 2002.
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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 BASES_DWA2002321_HPP
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# define BASES_DWA2002321_HPP
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# include <boost/python/detail/prefix.hpp>
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# include <boost/type_traits/object_traits.hpp>
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# include <boost/python/detail/type_list.hpp>
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# include <boost/mpl/if.hpp>
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# include <boost/mpl/bool.hpp>
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# include <boost/preprocessor/enum_params_with_a_default.hpp>
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# include <boost/preprocessor/enum_params.hpp>
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namespace boost { namespace python {
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# define BOOST_PYTHON_BASE_PARAMS BOOST_PP_ENUM_PARAMS_Z(1, BOOST_PYTHON_MAX_BASES, Base)
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// A type list for specifying bases
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template < BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(BOOST_PYTHON_MAX_BASES, typename Base, mpl::void_) >
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struct bases : detail::type_list< BOOST_PYTHON_BASE_PARAMS >::type
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{};
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namespace detail
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{
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# ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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template <class T> struct specifies_bases
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: mpl::false_
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{
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};
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template < BOOST_PP_ENUM_PARAMS_Z(1, BOOST_PYTHON_MAX_BASES, class Base) >
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struct specifies_bases< bases< BOOST_PYTHON_BASE_PARAMS > >
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: mpl::true_
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{
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};
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# else
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template < BOOST_PP_ENUM_PARAMS(BOOST_PYTHON_MAX_BASES, class Base) >
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static char is_bases_helper(bases< BOOST_PYTHON_BASE_PARAMS > const&);
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static char (& is_bases_helper(...) )[256];
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template <class T>
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struct specifies_bases
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{
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private:
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static typename add_reference<T>::type make();
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BOOST_STATIC_CONSTANT(bool, non_ref = !is_reference<T>::value);
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public:
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BOOST_STATIC_CONSTANT(bool, value = non_ref & (sizeof(is_bases_helper(make())) == 1));
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typedef mpl::bool_<value> type;
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};
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# endif
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template <class T, class Prev = bases<> >
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struct select_bases
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: mpl::if_<
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specifies_bases<T>
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, T
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, Prev
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>
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{
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};
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}
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# undef BOOST_PYTHON_BASE_PARAMS
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}} // namespace boost::python
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#endif // BASES_DWA2002321_HPP
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