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Remove mp_defer_if_valid; add mp_identity_t.

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This commit is contained in:
Peter Dimov
2015-07-26 17:43:00 +03:00
parent bd9e5f9c41
commit e51ed6cf3d
5 changed files with 39 additions and 35 deletions
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20
test/mp_defer.cpp
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@@ -8,19 +8,35 @@
#include <boost/mp11/utility.hpp>
#include <boost/mp11/integral.hpp>
#include <boost/core/lightweight_test_trait.hpp>
#include <type_traits>
template<class T> using add_pointer = T*;
template<class T> struct has_type
{
template<class U> static boost::mp_true f( boost::mp_identity<typename U::type>* );
template<class U> static boost::mp_false f( ... );
using type = decltype( f<T>(0) );
static const auto value = type::value;
};
using boost::mp_defer;
template<class T> using add_pointer_impl = mp_defer<add_pointer, T>;
template<class T> using add_pointer = T*;
template<class... T> using add_pointer_impl = mp_defer<add_pointer, T...>;
int main()
{
BOOST_TEST_TRAIT_TRUE((has_type<add_pointer_impl<void>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<add_pointer_impl<void>::type, void*>));
BOOST_TEST_TRAIT_TRUE((has_type<add_pointer_impl<int>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<add_pointer_impl<int>::type, int*>));
BOOST_TEST_TRAIT_FALSE((has_type<add_pointer_impl<>>));
BOOST_TEST_TRAIT_FALSE((has_type<add_pointer_impl<void, void>>));
return boost::report_errors();
}