ceph/src/boost/libs/hana/example/struct/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/define_struct.hpp>
   7 #include <boost/hana/fold_left.hpp>
   8 #include <boost/hana/second.hpp>
   9 namespace hana = boost::hana;
  10
  11
  12 struct Classroom {
  13     BOOST_HANA_DEFINE_STRUCT(Classroom,
  14         (unsigned short, boys),
  15         (unsigned short, girls)
  16     );
  17 };
  18
  19 int main() {
  20     constexpr Classroom compsci{20, 3};
  21
  22     BOOST_HANA_CONSTEXPR_CHECK(
  23         hana::fold_left(compsci, 0, [](auto total, auto member) {
  24             // first(member) is the name of the member, here
  25             // "boys" or "girls", and second(member) is its value.
  26             return hana::second(member) + total;
  27         }) == 23
  28     );
  29 }