ceph/src/boost/libs/hana/example/unfold_right.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/if.hpp>
   8 #include <boost/hana/integral_constant.hpp>
   9 #include <boost/hana/minus.hpp>
  10 #include <boost/hana/optional.hpp>
  11 #include <boost/hana/pair.hpp>
  12 #include <boost/hana/tuple.hpp>
  13 #include <boost/hana/unfold_right.hpp>
  14 namespace hana = boost::hana;
  15
  16
  17 BOOST_HANA_CONSTANT_CHECK(
  18     hana::unfold_right<hana::tuple_tag>(hana::int_c<10>, [](auto x) {
  19         return hana::if_(x == hana::int_c<0>,
  20             hana::nothing,
  21             hana::just(hana::make_pair(x, x - hana::int_c<1>))
  22         );
  23     })
  24     ==
  25     hana::tuple_c<int, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1>
  26 );
  27
  28 int main() { }