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hana/example/type/trait.cpp
2014-08-05 10:37:54 -04:00

33 lines
1.0 KiB
C++

/*
@copyright Louis Dionne 2014
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#include <boost/hana/detail/assert.hpp>
#include <boost/hana/detail/constexpr.hpp>
#include <boost/hana/ext/std/integral_constant.hpp>
#include <boost/hana/integral.hpp>
#include <boost/hana/type.hpp>
#include <type_traits>
using namespace boost::hana;
int main() {
//! [liftable]
using operators::operator!; // required to negate the result of std::is_integral
BOOST_HANA_CONSTANT_ASSERT(trait<std::is_integral>(type<int>));
BOOST_HANA_CONSTANT_ASSERT(!trait<std::is_integral>(type<float>));
//! [liftable]
//! [nonliftable]
BOOST_HANA_CONSTEXPR_LAMBDA auto extent = [](auto t, auto n) {
return std::extent<typename decltype(t)::type, n()>{};
};
BOOST_HANA_CONSTANT_ASSERT(extent(type<char>, int_<1>) == int_<0>);
BOOST_HANA_CONSTANT_ASSERT(extent(type<char[1][2]>, int_<1>) == int_<2>);
//! [nonliftable]
}