mirror of
https://github.com/boostorg/hana.git
synced 2026-01-24 05:52:14 +00:00
59 lines
1.5 KiB
C++
59 lines
1.5 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/assert.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/ext/boost/mpl/vector.hpp>
|
|
#include <boost/hana/ext/std/integral_constant.hpp>
|
|
#include <boost/hana/integral_constant.hpp>
|
|
#include <boost/hana/tuple.hpp>
|
|
|
|
#include <boost/mpl/fold.hpp>
|
|
#include <boost/mpl/if.hpp>
|
|
#include <boost/mpl/int.hpp>
|
|
#include <boost/mpl/next.hpp>
|
|
#include <boost/mpl/placeholders.hpp>
|
|
#include <boost/mpl/vector.hpp>
|
|
|
|
#include <type_traits>
|
|
namespace hana = boost::hana;
|
|
namespace mpl = boost::mpl;
|
|
|
|
|
|
namespace with_mpl {
|
|
//! [mpl]
|
|
using types = mpl::vector<long, float, short, float, long, long double>;
|
|
using number_of_floats = mpl::fold<
|
|
types,
|
|
mpl::int_<0>,
|
|
mpl::if_<std::is_floating_point<mpl::_2>,
|
|
mpl::next<mpl::_1>,
|
|
mpl::_1
|
|
>
|
|
>::type;
|
|
static_assert(number_of_floats::value == 3, "");
|
|
//! [mpl]
|
|
}
|
|
|
|
namespace with_hana {
|
|
//! [hana]
|
|
constexpr auto types = hana::tuple_t<long, float, short, float, long, long double>;
|
|
BOOST_HANA_CONSTEXPR_LAMBDA auto number_of_floats = hana::foldl(
|
|
types,
|
|
hana::int_<0>,
|
|
[](auto count, auto t) {
|
|
return hana::if_(hana::trait<std::is_floating_point>(t),
|
|
count + hana::int_<1>,
|
|
count
|
|
);
|
|
}
|
|
);
|
|
BOOST_HANA_CONSTANT_CHECK(number_of_floats == hana::int_<3>);
|
|
//! [hana]
|
|
}
|
|
|
|
int main() { }
|