ceph/src/boost/libs/hana/example/ext/boost/mpl/list/foldable.cpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #include <boost/hana/assert.hpp>
   6 #include <boost/hana/equal.hpp>
   7 #include <boost/hana/ext/boost/mpl/list.hpp>
   8 #include <boost/hana/ext/std/integral_constant.hpp>
   9 #include <boost/hana/fold_left.hpp>
  10 #include <boost/hana/if.hpp>
  11 #include <boost/hana/integral_constant.hpp>
  12 #include <boost/hana/plus.hpp>
  13 #include <boost/hana/type.hpp>
  14
  15 #include <boost/mpl/list.hpp>
  16 #include <type_traits>
  17 namespace hana = boost::hana;
  18 namespace mpl = boost::mpl;
  19
  20
  21 auto types = mpl::list<long, float, short, float, long, long double>{};
  22 auto number_of_floats = hana::fold_left(types, hana::int_c<0>, [](auto count, auto t) {
  23     return hana::if_(hana::trait<std::is_floating_point>(t),
  24         count + hana::int_c<1>,
  25         count
  26     );
  27 });
  28
  29 BOOST_HANA_CONSTANT_CHECK(number_of_floats == hana::int_c<3>);
  30
  31 int main() { }