libs/hana/example/flatten.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/flatten.hpp>
   8 #include <boost/hana/optional.hpp>
   9 #include <boost/hana/tuple.hpp>
  10 namespace hana = boost::hana;
  11
  12
  13 static_assert(
  14     hana::flatten(hana::make_tuple(hana::make_tuple(1, 2, 3),
  15                                    hana::make_tuple(4, 5),
  16                                    hana::make_tuple(6, 7, 8, 9)))
  17     ==
  18     hana::make_tuple(1, 2, 3, 4, 5, 6, 7, 8, 9)
  19 , "");
  20
  21 BOOST_HANA_CONSTANT_CHECK(hana::flatten(hana::nothing) == hana::nothing);
  22 static_assert(hana::flatten(hana::just(hana::just(1))) == hana::just(1), "");
  23 BOOST_HANA_CONSTANT_CHECK(hana::flatten(hana::just(hana::nothing)) == hana::nothing);
  24
  25 int main() { }