forked from boostorg/mp11
47 lines
1.3 KiB
C++
47 lines
1.3 KiB
C++
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// Copyright 2015-2017 Peter Dimov.
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//
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// Distributed under the Boost Software License, Version 1.0.
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//
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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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#include <boost/mp11/utility.hpp>
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#include <boost/mp11/integral.hpp>
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#include <boost/core/lightweight_test_trait.hpp>
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#include <type_traits>
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using boost::mp11::mp_identity;
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using boost::mp11::mp_true;
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using boost::mp11::mp_false;
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template<class T> struct has_type
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{
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template<class U> static mp_true f( mp_identity<typename U::type>* );
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template<class U> static mp_false f( ... );
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using type = decltype( f<T>(0) );
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static const bool value = type::value;
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};
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using boost::mp11::mp_defer;
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template<class T> using add_pointer = T*;
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template<class... T> using add_pointer_impl = mp_defer<add_pointer, T...>;
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int main()
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{
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BOOST_TEST_TRAIT_TRUE((has_type<add_pointer_impl<void>>));
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BOOST_TEST_TRAIT_TRUE((std::is_same<add_pointer_impl<void>::type, void*>));
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BOOST_TEST_TRAIT_TRUE((has_type<add_pointer_impl<int>>));
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BOOST_TEST_TRAIT_TRUE((std::is_same<add_pointer_impl<int>::type, int*>));
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BOOST_TEST_TRAIT_FALSE((has_type<add_pointer_impl<>>));
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BOOST_TEST_TRAIT_FALSE((has_type<add_pointer_impl<void, void>>));
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return boost::report_errors();
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}
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