54 lines
1.4 KiB
C++
54 lines
1.4 KiB
C++
// Copyright David Abrahams 2005.
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// Distributed under the Boost Software License, Version 1.0.
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// (See 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 BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP
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#define BOOST_PARAMETER_AUX_RESULT_OF0_DWA2005511_HPP
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#include <boost/parameter/aux_/use_default_tag.hpp>
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#include <boost/parameter/config.hpp>
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#include <boost/utility/result_of.hpp>
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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#include <boost/mp11/utility.hpp>
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#include <type_traits>
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#else
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#include <boost/mpl/if.hpp>
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#include <boost/type_traits/is_void.hpp>
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#endif
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namespace boost { namespace parameter { namespace aux {
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// A metafunction returning the result of invoking
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// a nullary function object of the given type.
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template <typename F>
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class result_of0
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{
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#if defined(BOOST_NO_RESULT_OF)
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typedef typename F::result_type result_of_F;
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#else
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typedef typename ::boost::result_of<F()>::type result_of_F;
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#endif
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public:
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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using type = ::boost::mp11::mp_if<
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::std::is_void<result_of_F>
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#else
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typedef typename ::boost::mpl::if_<
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::boost::is_void<result_of_F>
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#endif
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, ::boost::parameter::aux::use_default_tag
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, result_of_F
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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>;
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#else
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>::type type;
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#endif
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};
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}}} // namespace boost::parameter::aux
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#endif // include guard
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